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Contents Internet The Internet (or internet)[a] is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP)[b] to communicate between networks and devices. It is a network of networks that comprises private, public, academic, business, and government networks of local to global scope, linked by electronic, wireless, and optical networking technologies. The Internet carries a vast range of information services and resources, such as the interlinked hypertext documents and applications of the World Wide Web (WWW), electronic mail, discussion groups, internet telephony, streaming media and file sharing. Most traditional communication media, including telephone, radio, television, paper mail, newspapers, and print publishing, have been transformed by the Internet, giving rise to new media such as email, online music, digital newspapers, news aggregators, and audio and video streaming websites. The Internet has enabled and accelerated new forms of personal interaction through instant messaging, Internet forums, and social networking services. Online shopping has also grown to occupy a significant market across industries, enabling firms to extend brick and mortar presences to serve larger markets. Business-to-business and financial services on the Internet affect supply chains across entire industries. The origins of the Internet date back to research that enabled the time-sharing of computer resources, the development of packet switching, and the design of computer networks for data communication. The set of communication protocols to enable internetworking on the Internet arose from research and development commissioned in the 1970s by the Defense Advanced Research Projects Agency (DARPA) of the United States Department of Defense in collaboration with universities and researchers across the United States and in the United Kingdom and France. The Internet has no single centralized governance in either technological implementation or policies for access and usage. Each constituent network sets its own policies. The overarching definitions of the two principal name spaces on the Internet, the Internet Protocol address (IP address) space and the Domain Name System (DNS), are directed by a maintainer organization, the Internet Corporation for Assigned Names and Numbers (ICANN). The technical underpinning and standardization of the core protocols is an activity of the non-profit Internet Engineering Task Force (IETF). Terminology The word internetted was used as early as 1849, meaning interconnected or interwoven. The word Internet was used in 1945 by the United States War Department in a radio operator's manual, and in 1974 as the shorthand form of Internetwork. Today, the term Internet most commonly refers to the global system of interconnected computer networks, though it may also refer to any group of smaller networks. The word Internet may be capitalized as a proper noun, although this is becoming less common. This reflects the tendency in English to capitalize new terms and move them to lowercase as they become familiar. The word is sometimes still capitalized to distinguish the global internet from smaller networks, though many publications, including the AP Stylebook since 2016, recommend the lowercase form in every case. In 2016, the Oxford English Dictionary found that, based on a study of around 2.5 billion printed and online sources, "Internet" was capitalized in 54% of cases. The terms Internet and World Wide Web are often used interchangeably; it is common to speak of "going on the Internet" when using a web browser to view web pages. However, the World Wide Web, or the Web, is only one of a large number of Internet services. It is the global collection of web pages, documents and other web resources linked by hyperlinks and URLs. History In the 1960s, computer scientists began developing systems for time-sharing of computer resources. J. C. R. Licklider proposed the idea of a universal network while working at Bolt Beranek & Newman and, later, leading the Information Processing Techniques Office at the Advanced Research Projects Agency (ARPA) of the United States Department of Defense. Research into packet switching,[c] one of the fundamental Internet technologies, started in the work of Paul Baran at RAND in the early 1960s and, independently, Donald Davies at the United Kingdom's National Physical Laboratory in 1965. After the Symposium on Operating Systems Principles in 1967, packet switching from the proposed NPL network was incorporated into the design of the ARPANET, an experimental resource sharing network proposed by ARPA. ARPANET development began with two network nodes which were interconnected between the University of California, Los Angeles and the Stanford Research Institute on 29 October 1969. The third site was at the University of California, Santa Barbara, followed by the University of Utah. By the end of 1971, 15 sites were connected to the young ARPANET. Thereafter, the ARPANET gradually developed into a decentralized communications network, connecting remote centers and military bases in the United States. Other user networks and research networks, such as the Merit Network and CYCLADES, were developed in the late 1960s and early 1970s. Early international collaborations for the ARPANET were rare. Connections were made in 1973 to Norway (NORSAR and, later, NDRE) and to Peter Kirstein's research group at University College London, which provided a gateway to British academic networks, the first internetwork for resource sharing. ARPA projects, the International Network Working Group and commercial initiatives led to the development of various protocols and standards by which multiple separate networks could become a single network, or a network of networks. In 1974, Vint Cerf at Stanford University and Bob Kahn at DARPA published a proposal for "A Protocol for Packet Network Intercommunication". Cerf and his graduate students used the term internet as a shorthand for internetwork in RFC 675. The Internet Experiment Notes and later RFCs repeated this use. The work of Louis Pouzin and Robert Metcalfe had important influences on the resulting TCP/IP design. National PTTs and commercial providers developed the X.25 standard and deployed it on public data networks. The ARPANET initially served as a backbone for the interconnection of regional academic and military networks in the United States to enable resource sharing. Access to the ARPANET was expanded in 1981 when the National Science Foundation (NSF) funded the Computer Science Network (CSNET). In 1982, the Internet Protocol Suite (TCP/IP) was standardized, which facilitated worldwide proliferation of interconnected networks. TCP/IP network access expanded again in 1986 when the National Science Foundation Network (NSFNet) provided access to supercomputer sites in the United States for researchers, first at speeds of 56 kbit/s and later at 1.5 Mbit/s and 45 Mbit/s. The NSFNet expanded into academic and research organizations in Europe, Australia, New Zealand and Japan in 1988–89. Although other network protocols such as UUCP and PTT public data networks had global reach well before this time, this marked the beginning of the Internet as an intercontinental network. Commercial Internet service providers emerged in 1989 in the United States and Australia. The ARPANET was decommissioned in 1990. The linking of commercial networks and enterprises by the early 1990s, as well as the advent of the World Wide Web, marked the beginning of the transition to the modern Internet. Steady advances in semiconductor technology and optical networking created new economic opportunities for commercial involvement in the expansion of the network in its core and for delivering services to the public. In mid-1989, MCI Mail and Compuserve established connections to the Internet, delivering email and public access products to the half million users of the Internet. Just months later, on 1 January 1990, PSInet launched an alternate Internet backbone for commercial use; one of the networks that added to the core of the commercial Internet of later years. In March 1990, the first high-speed T1 (1.5 Mbit/s) link between the NSFNET and Europe was installed between Cornell University and CERN, allowing much more robust communications than were capable with satellites. Later in 1990, Tim Berners-Lee began writing WorldWideWeb, the first web browser, after two years of lobbying CERN management. By Christmas 1990, Berners-Lee had built all the tools necessary for a working Web: the HyperText Transfer Protocol (HTTP) 0.9, the HyperText Markup Language (HTML), the first Web browser (which was also an HTML editor and could access Usenet newsgroups and FTP files), the first HTTP server software (later known as CERN httpd), the first web server, and the first Web pages that described the project itself. In 1991 the Commercial Internet eXchange was founded, allowing PSInet to communicate with the other commercial networks CERFnet and Alternet. Stanford Federal Credit Union was the first financial institution to offer online Internet banking services to all of its members in October 1994. In 1996, OP Financial Group, also a cooperative bank, became the second online bank in the world and the first in Europe. By 1995, the Internet was fully commercialized in the U.S. when the NSFNet was decommissioned, removing the last restrictions on use of the Internet to carry commercial traffic. As technology advanced and commercial opportunities fueled reciprocal growth, the volume of Internet traffic started experiencing similar characteristics as that of the scaling of MOS transistors, exemplified by Moore's law, doubling every 18 months. This growth, formalized as Edholm's law, was catalyzed by advances in MOS technology, laser light wave systems, and noise performance. Since 1995, the Internet has tremendously impacted culture and commerce, including the rise of near-instant communication by email, instant messaging, telephony (Voice over Internet Protocol or VoIP), two-way interactive video calls, and the World Wide Web. Increasing amounts of data are transmitted at higher and higher speeds over fiber optic networks operating at 1 Gbit/s, 10 Gbit/s, or more. The Internet continues to grow, driven by ever-greater amounts of online information and knowledge, commerce, entertainment and social networking services. During the late 1990s, it was estimated that traffic on the public Internet grew by 100 percent per year, while the mean annual growth in the number of Internet users was thought to be between 20% and 50%. This growth is often attributed to the lack of central administration, which allows organic growth of the network, as well as the non-proprietary nature of the Internet protocols, which encourages vendor interoperability and prevents any one company from exerting too much control over the network. In November 2006, the Internet was included on USA Today's list of the New Seven Wonders. As of 31 March 2011[update], the estimated total number of Internet users was 2.095 billion (30% of world population). It is estimated that in 1993 the Internet carried only 1% of the information flowing through two-way telecommunication. By 2000 this figure had grown to 51%, and by 2007 more than 97% of all telecommunicated information was carried over the Internet. Modern smartphones can access the Internet through cellular carrier networks, and internet usage by mobile and tablet devices exceeded desktop worldwide for the first time in October 2016. As of 2018[update], 80% of the world's population were covered by a 4G network. The International Telecommunication Union (ITU) estimated that, by the end of 2017, 48% of individual users regularly connect to the Internet, up from 34% in 2012. Mobile Internet connectivity has played an important role in expanding access in recent years, especially in Asia and the Pacific and in Africa. The number of unique mobile cellular subscriptions increased from 3.9 billion in 2012 to 4.8 billion in 2016, two-thirds of the world's population, with more than half of subscriptions located in Asia and the Pacific. The limits that users face on accessing information via mobile applications coincide with a broader process of fragmentation of the Internet. Fragmentation restricts access to media content and tends to affect the poorest users the most. One solution, zero-rating, is the practice of Internet service providers allowing users free connectivity to access specific content or applications without cost. Social impact The Internet has enabled new forms of social interaction, activities, and social associations, giving rise to the scholarly study of the sociology of the Internet. Between 2000 and 2009, the number of Internet users globally rose from 390 million to 1.9 billion. By 2010, 22% of the world's population had access to computers with 1 billion Google searches every day, 300 million Internet users reading blogs, and 2 billion videos viewed daily on YouTube. In 2014 the world's Internet users surpassed 3 billion or 44 percent of world population, but two-thirds came from the richest countries, with 78 percent of Europeans using the Internet, followed by 57 percent of the Americas. However, by 2018, Asia alone accounted for 51% of all Internet users, with 2.2 billion out of the 4.3 billion Internet users in the world. China's Internet users surpassed a major milestone in 2018, when the country's Internet regulatory authority, China Internet Network Information Centre, announced that China had 802 million users. China was followed by India, with some 700 million users, with the United States third with 275 million users. However, in terms of penetration, in 2022, China had a 70% penetration rate compared to India's 60% and the United States's 90%. In 2022, 54% of the world's Internet users were based in Asia, 14% in Europe, 7% in North America, 10% in Latin America and the Caribbean, 11% in Africa, 4% in the Middle East and 1% in Oceania. In 2019, Kuwait, Qatar, the Falkland Islands, Bermuda and Iceland had the highest Internet penetration by the number of users, with 93% or more of the population with access. As of 2022, it was estimated that 5.4 billion people use the Internet, more than two-thirds of the world's population. Early computer systems were limited to the characters in the American Standard Code for Information Interchange (ASCII), a subset of the Latin alphabet. After English (27%), the most requested languages on the World Wide Web are Chinese (25%), Spanish (8%), Japanese (5%), Portuguese and German (4% each), Arabic, French and Russian (3% each), and Korean (2%). Modern character encoding standards, such as Unicode, allow for development and communication in the world's widely used languages. However, some glitches such as mojibake (incorrect display of some languages' characters) still remain. Several neologisms exist that refer to Internet users: Netizen (as in "citizen of the net") refers to those actively involved in improving online communities, the Internet in general or surrounding political affairs and rights such as free speech, Internaut refers to operators or technically highly capable users of the Internet, digital citizen refers to a person using the Internet in order to engage in society, politics, and government participation. The Internet allows greater flexibility in working hours and location, especially with the spread of unmetered high-speed connections. The Internet can be accessed almost anywhere by numerous means, including through mobile Internet devices. Mobile phones, datacards, handheld game consoles and cellular routers allow users to connect to the Internet wirelessly.[citation needed] Educational material at all levels from pre-school (e.g. CBeebies) to post-doctoral (e.g. scholarly literature through Google Scholar) is available on websites. The internet has facilitated the development of virtual universities and distance education, enabling both formal and informal education. The Internet allows researchers to conduct research remotely via virtual laboratories, with profound changes in reach and generalizability of findings as well as in communication between scientists and in the publication of results. By the late 2010s the Internet had been described as "the main source of scientific information "for the majority of the global North population".: 111 Wikis have also been used in the academic community for sharing and dissemination of information across institutional and international boundaries. In those settings, they have been found useful for collaboration on grant writing, strategic planning, departmental documentation, and committee work. The United States Patent and Trademark Office uses a wiki to allow the public to collaborate on finding prior art relevant to examination of pending patent applications. Queens, New York has used a wiki to allow citizens to collaborate on the design and planning of a local park. The English Wikipedia has the largest user base among wikis on the World Wide Web and ranks in the top 10 among all sites in terms of traffic. The Internet has been a major outlet for leisure activity since its inception, with entertaining social experiments such as MUDs and MOOs being conducted on university servers, and humor-related Usenet groups receiving much traffic. Many Internet forums have sections devoted to games and funny videos. Another area of leisure activity on the Internet is multiplayer gaming. This form of recreation creates communities, where people of all ages and origins enjoy the fast-paced world of multiplayer games. These range from MMORPG to first-person shooters, from role-playing video games to online gambling. While online gaming has been around since the 1970s, modern modes of online gaming began with subscription services such as GameSpy and MPlayer. Streaming media is the real-time delivery of digital media for immediate consumption or enjoyment by end users. Streaming companies (such as Netflix, Disney+, Amazon's Prime Video, Mubi, Hulu, and Apple TV+) now dominate the entertainment industry, eclipsing traditional broadcasters. Audio streamers such as Spotify and Apple Music also have significant market share in the audio entertainment market. Video sharing websites are also a major factor in the entertainment ecosystem. YouTube was founded on 15 February 2005 and is now the leading website for free streaming video with more than two billion users. It uses a web player to stream and show video files. YouTube users watch hundreds of millions, and upload hundreds of thousands, of videos daily. Other video sharing websites include Vimeo, Instagram and TikTok.[citation needed] Although many governments have attempted to restrict both Internet pornography and online gambling, this has generally failed to stop their widespread popularity. A number of advertising-funded ostensible video sharing websites known as "tube sites" have been created to host shared pornographic video content. Due to laws requiring the documentation of the origin of pornography, these websites now largely operate in conjunction with pornographic movie studios and their own independent creator networks, acting as de-facto video streaming services. Major players in this field include the market leader Aylo, the operator of PornHub and numerous other branded sites, as well as other independent operators such as xHamster and Xvideos. As of 2023[update], Internet traffic to pornographic video sites rivalled that of mainstream video streaming and sharing services. Remote work is facilitated by tools such as groupware, virtual private networks, conference calling, videotelephony, and VoIP so that work may be performed from any location, such as the worker's home.[citation needed] The spread of low-cost Internet access in developing countries has opened up new possibilities for peer-to-peer charities, which allow individuals to contribute small amounts to charitable projects for other individuals. Websites, such as DonorsChoose and GlobalGiving, allow small-scale donors to direct funds to individual projects of their choice. A popular twist on Internet-based philanthropy is the use of peer-to-peer lending for charitable purposes. Kiva pioneered this concept in 2005, offering the first web-based service to publish individual loan profiles for funding. The low cost and nearly instantaneous sharing of ideas, knowledge, and skills have made collaborative work dramatically easier, with the help of collaborative software, which allow groups to easily form, cheaply communicate, and share ideas. An example of collaborative software is the free software movement, which has produced, among other things, Linux, Mozilla Firefox, and OpenOffice.org (later forked into LibreOffice).[citation needed] Content management systems allow collaborating teams to work on shared sets of documents simultaneously without accidentally destroying each other's work.[citation needed] The internet also allows for cloud computing, virtual private networks, remote desktops, and remote work.[citation needed] The online disinhibition effect describes the tendency of many individuals to behave more stridently or offensively online than they would in person. A significant number of feminist women have been the target of various forms of harassment, including insults and hate speech, to, in extreme cases, rape and death threats, in response to posts they have made on social media. Social media companies have been criticized in the past for not doing enough to aid victims of online abuse. Children also face dangers online such as cyberbullying and approaches by sexual predators, who sometimes pose as children themselves. Due to naivety, they may also post personal information about themselves online, which could put them or their families at risk unless warned not to do so. Many parents choose to enable Internet filtering or supervise their children's online activities in an attempt to protect their children from pornography or violent content on the Internet. The most popular social networking services commonly forbid users under the age of 13. However, these policies can be circumvented by registering an account with a false birth date, and a significant number of children aged under 13 join such sites.[citation needed] Social networking services for younger children, which claim to provide better levels of protection for children, also exist. Internet usage has been correlated to users' loneliness. Lonely people tend to use the Internet as an outlet for their feelings and to share their stories with others, such as in the "I am lonely will anyone speak to me" thread.[citation needed] Cyberslacking can become a drain on corporate resources; employees spend a significant amount of time surfing the Web while at work. Internet addiction disorder is excessive computer use that interferes with daily life. Nicholas G. Carr believes that Internet use has other effects on individuals, for instance improving skills of scan-reading and interfering with the deep thinking that leads to true creativity. Electronic business encompasses business processes spanning the entire value chain: purchasing, supply chain management, marketing, sales, customer service, and business relationship. E-commerce seeks to add revenue streams using the Internet to build and enhance relationships with clients and partners. According to International Data Corporation, the size of worldwide e-commerce, when global business-to-business and -consumer transactions are combined, equate to $16 trillion in 2013. A report by Oxford Economics added those two together to estimate the total size of the digital economy at $20.4 trillion, equivalent to roughly 13.8% of global sales. While much has been written of the economic advantages of Internet-enabled commerce, there is also evidence that some aspects of the Internet such as maps and location-aware services may serve to reinforce economic inequality and the digital divide. Electronic commerce may be responsible for consolidation and the decline of mom-and-pop, brick and mortar businesses resulting in increases in income inequality. A 2013 Institute for Local Self-Reliance report states that brick-and-mortar retailers employ 47 people for every $10 million in sales, while Amazon employs only 14. Similarly, the 700-employee room rental start-up Airbnb was valued at $10 billion in 2014, about half as much as Hilton Worldwide, which employs 152,000 people. At that time, Uber employed 1,000 full-time employees and was valued at $18.2 billion, about the same valuation as Avis Rent a Car and The Hertz Corporation combined, which together employed almost 60,000 people. Advertising on popular web pages can be lucrative, and e-commerce. Online advertising is a form of marketing and advertising which uses the Internet to deliver promotional marketing messages to consumers. It includes email marketing, search engine marketing (SEM), social media marketing, many types of display advertising (including web banner advertising), and mobile advertising. In 2011, Internet advertising revenues in the United States surpassed those of cable television and nearly exceeded those of broadcast television.: 19 Many common online advertising practices are controversial and increasingly subject to regulation. The Internet has achieved new relevance as a political tool. The presidential campaign of Howard Dean in 2004 in the United States was notable for its success in soliciting donation via the Internet. Many political groups use the Internet to achieve a new method of organizing for carrying out their mission, having given rise to Internet activism. Social media websites, such as Facebook and Twitter, helped people organize the Arab Spring, by helping activists organize protests, communicate grievances, and disseminate information. Many have understood the Internet as an extension of the Habermasian notion of the public sphere, observing how network communication technologies provide something like a global civic forum. However, incidents of politically motivated Internet censorship have now been recorded in many countries, including western democracies. E-government is the use of technological communications devices, such as the Internet, to provide public services to citizens and other persons in a country or region. E-government offers opportunities for more direct and convenient citizen access to government and for government provision of services directly to citizens. Cybersectarianism is a new organizational form that involves: highly dispersed small groups of practitioners that may remain largely anonymous within the larger social context and operate in relative secrecy, while still linked remotely to a larger network of believers who share a set of practices and texts, and often a common devotion to a particular leader. Overseas supporters provide funding and support; domestic practitioners distribute tracts, participate in acts of resistance, and share information on the internal situation with outsiders. Collectively, members and practitioners of such sects construct viable virtual communities of faith, exchanging personal testimonies and engaging in the collective study via email, online chat rooms, and web-based message boards. In particular, the British government has raised concerns about the prospect of young British Muslims being indoctrinated into Islamic extremism by material on the Internet, being persuaded to join terrorist groups such as the so-called "Islamic State", and then potentially committing acts of terrorism on returning to Britain after fighting in Syria or Iraq.[citation needed] Applications and services The Internet carries many applications and services, most prominently the World Wide Web, including social media, electronic mail, mobile applications, multiplayer online games, Internet telephony, file sharing, and streaming media services. The World Wide Web is a global collection of documents, images, multimedia, applications, and other resources, logically interrelated by hyperlinks and referenced with Uniform Resource Identifiers (URIs), which provide a global system of named references. URIs symbolically identify services, web servers, databases, and the documents and resources that they can provide. HyperText Transfer Protocol (HTTP) is the main access protocol of the World Wide Web. Web services also use HTTP for communication between software systems for information transfer, sharing and exchanging business data and logistics and is one of many languages or protocols that can be used for communication on the Internet. World Wide Web browser software, such as Microsoft Edge, Mozilla Firefox, Opera, Apple's Safari, and Google Chrome, enable users to navigate from one web page to another via the hyperlinks embedded in the documents. These documents may also contain computer data, including graphics, sounds, text, video, multimedia and interactive content. Client-side scripts can include animations, games, office applications and scientific demonstrations. Email is an important communications service available via the Internet. The concept of sending electronic text messages between parties, analogous to mailing letters or memos, predates the creation of the Internet. Internet telephony is a common communications service realized with the Internet. The name of the principal internetworking protocol, the Internet Protocol, lends its name to voice over Internet Protocol (VoIP).[citation needed] VoIP systems now dominate many markets, being as easy and convenient as a traditional telephone, while having substantial cost savings, especially over long distances. File sharing is the practice of transferring large amounts of data in the form of computer files across the Internet, for example via file servers. The load of bulk downloads to many users can be eased by the use of "mirror" servers or peer-to-peer networks. Access to the file may be controlled by user authentication, the transit of the file over the Internet may be obscured by encryption, and money may change hands for access to the file. The price can be paid by the remote charging of funds from, for example, a credit card whose details are also passed—usually fully encrypted—across the Internet. The origin and authenticity of the file received may be checked by a digital signature. Governance The Internet is a global network that comprises many voluntarily interconnected autonomous networks. It operates without a central governing body. The technical underpinning and standardization of the core protocols (IPv4 and IPv6) is an activity of the Internet Engineering Task Force (IETF), a non-profit organization of loosely affiliated international participants that anyone may associate with by contributing technical expertise. While the hardware components in the Internet infrastructure can often be used to support other software systems, it is the design and the standardization process of the software that characterizes the Internet and provides the foundation for its scalability and success. The responsibility for the architectural design of the Internet software systems has been assumed by the IETF. The IETF conducts standard-setting work groups, open to any individual, about the various aspects of Internet architecture. The resulting contributions and standards are published as Request for Comments (RFC) documents on the IETF web site. The principal methods of networking that enable the Internet are contained in specially designated RFCs that constitute the Internet Standards. Other less rigorous documents are simply informative, experimental, or historical, or document the best current practices when implementing Internet technologies. To maintain interoperability, the principal name spaces of the Internet are administered by the Internet Corporation for Assigned Names and Numbers (ICANN). ICANN is governed by an international board of directors drawn from across the Internet technical, business, academic, and other non-commercial communities. The organization coordinates the assignment of unique identifiers for use on the Internet, including domain names, IP addresses, application port numbers in the transport protocols, and many other parameters. Globally unified name spaces are essential for maintaining the global reach of the Internet. This role of ICANN distinguishes it as perhaps the only central coordinating body for the global Internet. The National Telecommunications and Information Administration, an agency of the United States Department of Commerce, had final approval over changes to the DNS root zone until the IANA stewardship transition on 1 October 2016. Regional Internet registries (RIRs) were established for five regions of the world to assign IP address blocks and other Internet parameters to local registries, such as Internet service providers, from a designated pool of addresses set aside for each region:[citation needed] The Internet Society (ISOC) was founded in 1992 with a mission to "assure the open development, evolution and use of the Internet for the benefit of all people throughout the world". Its members include individuals as well as corporations, organizations, governments, and universities. Among other activities ISOC provides an administrative home for a number of less formally organized groups that are involved in developing and managing the Internet, including: the Internet Engineering Task Force (IETF), Internet Architecture Board (IAB), Internet Engineering Steering Group (IESG), Internet Research Task Force (IRTF), and Internet Research Steering Group (IRSG). On 16 November 2005, the United Nations-sponsored World Summit on the Information Society in Tunis established the Internet Governance Forum (IGF) to discuss Internet-related issues.[citation needed] Infrastructure The communications infrastructure of the Internet consists of its hardware components and a system of software layers that control various aspects of the architecture. As with any computer network, the Internet physically consists of routers, media (such as cabling and radio links), repeaters, and modems. However, as an example of internetworking, many of the network nodes are not necessarily Internet equipment per se. Internet packets are carried by other full-fledged networking protocols, with the Internet acting as a homogeneous networking standard, running across heterogeneous hardware, with the packets guided to their destinations by IP routers.[citation needed] Internet service providers (ISPs) establish worldwide connectivity between individual networks at various levels of scope. At the top of the routing hierarchy are the tier 1 networks, large telecommunication companies that exchange traffic directly with each other via very high speed fiber-optic cables and governed by peering agreements. Tier 2 and lower-level networks buy Internet transit from other providers to reach at least some parties on the global Internet, though they may also engage in peering. End-users who only access the Internet when needed to perform a function or obtain information, represent the bottom of the routing hierarchy.[citation needed] An ISP may use a single upstream provider for connectivity, or implement multihoming to achieve redundancy and load balancing. Internet exchange points are major traffic exchanges with physical connections to multiple ISPs. Large organizations, such as academic institutions, large enterprises, and governments, may perform the same function as ISPs, engaging in peering and purchasing transit on behalf of their internal networks. Research networks tend to interconnect with large subnetworks such as GEANT, GLORIAD, Internet2, and the UK's national research and education network, JANET.[citation needed] Common methods of Internet access by users include broadband over coaxial cable, fiber optics or copper wires, Wi-Fi, satellite, and cellular telephone technology.[citation needed] Grassroots efforts have led to wireless community networks. Commercial Wi-Fi services that cover large areas are available in many cities, such as New York, London, Vienna, Toronto, San Francisco, Philadelphia, Chicago and Pittsburgh. Most servers that provide internet services are today hosted in data centers, and content is often accessed through high-performance content delivery networks. Colocation centers often host private peering connections between their customers, internet transit providers, cloud providers, meet-me rooms for connecting customers together, Internet exchange points, and landing points and terminal equipment for fiber optic submarine communication cables, connecting the internet. Internet Protocol Suite The Internet standards describe a framework known as the Internet protocol suite (also called TCP/IP, based on the first two components.) This is a suite of protocols that are ordered into a set of four conceptional layers by the scope of their operation, originally documented in RFC 1122 and RFC 1123:[citation needed] The most prominent component of the Internet model is the Internet Protocol. IP enables internetworking, essentially establishing the Internet itself. Two versions of the Internet Protocol exist, IPv4 and IPv6.[citation needed] Aside from the complex array of physical connections that make up its infrastructure, the Internet is facilitated by bi- or multi-lateral commercial contracts (e.g., peering agreements), and by technical specifications or protocols that describe the exchange of data over the network.[citation needed] For locating individual computers on the network, the Internet provides IP addresses. IP addresses are used by the Internet infrastructure to direct internet packets to their destinations. They consist of fixed-length numbers, which are found within the packet. IP addresses are generally assigned to equipment either automatically via Dynamic Host Configuration Protocol, or are configured.[citation needed] Domain Name Systems convert user-inputted domain names (e.g. "en.wikipedia.org") into IP addresses.[citation needed] Internet Protocol version 4 (IPv4) defines an IP address as a 32-bit number. IPv4 is the initial version used on the first generation of the Internet and is still in dominant use. It was designed in 1981 to address up to ≈4.3 billion (109) hosts. However, the explosive growth of the Internet has led to IPv4 address exhaustion, which entered its final stage in 2011, when the global IPv4 address allocation pool was exhausted. Because of the growth of the Internet and the depletion of available IPv4 addresses, a new version of IP IPv6, was developed in the mid-1990s, which provides vastly larger addressing capabilities and more efficient routing of Internet traffic. IPv6 uses 128 bits for the IP address and was standardized in 1998. IPv6 deployment has been ongoing since the mid-2000s and is currently in growing deployment around the world, since Internet address registries began to urge all resource managers to plan rapid adoption and conversion. By design, IPv6 is not directly interoperable with IPv4. Instead, it establishes a parallel version of the Internet not directly accessible with IPv4 software. Thus, translation facilities exist for internetworking, and some nodes have duplicate networking software for both networks. Essentially all modern computer operating systems support both versions of the Internet Protocol.[citation needed] Network infrastructure, however, has been lagging in this development.[citation needed] A subnet or subnetwork is a logical subdivision of an IP network.: 1, 16 Computers that belong to a subnet are addressed with an identical most-significant bit-group in their IP addresses. This results in the logical division of an IP address into two fields, the network number or routing prefix and the rest field or host identifier. The rest field is an identifier for a specific host or network interface.[citation needed] The routing prefix may be expressed in Classless Inter-Domain Routing (CIDR) notation written as the first address of a network, followed by a slash character (/), and ending with the bit-length of the prefix. For example, 198.51.100.0/24 is the prefix of the Internet Protocol version 4 network starting at the given address, having 24 bits allocated for the network prefix, and the remaining 8 bits reserved for host addressing. Addresses in the range 198.51.100.0 to 198.51.100.255 belong to this network. The IPv6 address specification 2001:db8::/32 is a large address block with 296 addresses, having a 32-bit routing prefix.[citation needed] For IPv4, a network may also be characterized by its subnet mask or netmask, which is the bitmask that when applied by a bitwise AND operation to any IP address in the network, yields the routing prefix. Subnet masks are also expressed in dot-decimal notation like an address. For example, 255.255.255.0 is the subnet mask for the prefix 198.51.100.0/24.[citation needed] Computers and routers use routing tables in their operating system to forward IP packets to reach a node on a different subnetwork. Routing tables are maintained by manual configuration or automatically by routing protocols. End-nodes typically use a default route that points toward an ISP providing transit, while ISP routers use the Border Gateway Protocol to establish the most efficient routing across the complex connections of the global Internet.[citation needed] The default gateway is the node that serves as the forwarding host (router) to other networks when no other route specification matches the destination IP address of a packet. Security Internet resources, hardware, and software components are the target of criminal or malicious attempts to gain unauthorized control to cause interruptions, commit fraud, engage in blackmail or access private information. Malware is malicious software used and distributed via the Internet. It includes computer viruses which are copied with the help of humans, computer worms which copy themselves automatically, software for denial of service attacks, ransomware, botnets, and spyware that reports on the activity and typing of users.[citation needed] Usually, these activities constitute cybercrime. Defense theorists have also speculated about the possibilities of hackers using cyber warfare using similar methods on a large scale. Malware poses serious problems to individuals and businesses on the Internet. According to Symantec's 2018 Internet Security Threat Report (ISTR), malware variants number has increased to 669,947,865 in 2017, which is twice as many malware variants as in 2016. Cybercrime, which includes malware attacks as well as other crimes committed by computer, was predicted to cost the world economy US$6 trillion in 2021, and is increasing at a rate of 15% per year. Since 2021, malware has been designed to target computer systems that run critical infrastructure such as the electricity distribution network. Malware can be designed to evade antivirus software detection algorithms. The vast majority of computer surveillance involves the monitoring of data and traffic on the Internet. In the United States for example, under the Communications Assistance For Law Enforcement Act, all phone calls and broadband Internet traffic (emails, web traffic, instant messaging, etc.) are required to be available for unimpeded real-time monitoring by Federal law enforcement agencies. Under the Act, all U.S. telecommunications providers are required to install packet sniffing technology to allow Federal law enforcement and intelligence agencies to intercept all of their customers' broadband Internet and VoIP traffic.[d] The large amount of data gathered from packet capture requires surveillance software that filters and reports relevant information, such as the use of certain words or phrases, the access to certain types of web sites, or communicating via email or chat with certain parties. Agencies, such as the Information Awareness Office, NSA, GCHQ and the FBI, spend billions of dollars per year to develop, purchase, implement, and operate systems for interception and analysis of data. Similar systems are operated by Iranian secret police to identify and suppress dissidents. The required hardware and software were allegedly installed by German Siemens AG and Finnish Nokia. Some governments, such as those of Myanmar, Iran, North Korea, Mainland China, Saudi Arabia and the United Arab Emirates, restrict access to content on the Internet within their territories, especially to political and religious content, with domain name and keyword filters. In Norway, Denmark, Finland, and Sweden, major Internet service providers have voluntarily agreed to restrict access to sites listed by authorities. While this list of forbidden resources is supposed to contain only known child pornography sites, the content of the list is secret. Many countries, including the United States, have enacted laws against the possession or distribution of certain material, such as child pornography, via the Internet but do not mandate filter software. Many free or commercially available software programs, called content-control software are available to users to block offensive specific on individual computers or networks in order to limit access by children to pornographic material or depiction of violence.[citation needed] Performance As the Internet is a heterogeneous network, its physical characteristics, including, for example the data transfer rates of connections, vary widely. It exhibits emergent phenomena that depend on its large-scale organization. PB per monthYear020,00040,00060,00080,000100,000120,000140,000199019952000200520102015Petabytes per monthGlobal Internet Traffic Volume The volume of Internet traffic is difficult to measure because no single point of measurement exists in the multi-tiered, non-hierarchical topology. Traffic data may be estimated from the aggregate volume through the peering points of the Tier 1 network providers, but traffic that stays local in large provider networks may not be accounted for.[citation needed] An Internet blackout or outage can be caused by local signaling interruptions. Disruptions of submarine communications cables may cause blackouts or slowdowns to large areas, such as in the 2008 submarine cable disruption. Less-developed countries are more vulnerable due to the small number of high-capacity links. Land cables are also vulnerable, as in 2011 when a woman digging for scrap metal severed most connectivity for the nation of Armenia. Internet blackouts affecting almost entire countries can be achieved by governments as a form of Internet censorship, as in the blockage of the Internet in Egypt, whereby approximately 93% of networks were without access in 2011 in an attempt to stop mobilization for anti-government protests. Estimates of the Internet's electricity usage have been the subject of controversy, according to a 2014 peer-reviewed research paper that found claims differing by a factor of 20,000 published in the literature during the preceding decade, ranging from 0.0064 kilowatt hours per gigabyte transferred (kWh/GB) to 136 kWh/GB. The researchers attributed these discrepancies mainly to the year of reference (i.e. whether efficiency gains over time had been taken into account) and to whether "end devices such as personal computers and servers are included" in the analysis. In 2011, academic researchers estimated the overall energy used by the Internet to be between 170 and 307 GW, less than two percent of the energy used by humanity. This estimate included the energy needed to build, operate, and periodically replace the estimated 750 million laptops, a billion smart phones and 100 million servers worldwide as well as the energy that routers, cell towers, optical switches, Wi-Fi transmitters and cloud storage devices use when transmitting Internet traffic. According to a non-peer-reviewed study published in 2018 by The Shift Project (a French think tank funded by corporate sponsors), nearly 4% of global CO2 emissions could be attributed to global data transfer and the necessary infrastructure. The study also said that online video streaming alone accounted for 60% of this data transfer and therefore contributed to over 300 million tons of CO2 emission per year, and argued for new "digital sobriety" regulations restricting the use and size of video files. See also Notes References Sources Further reading External links |
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[SOURCE: https://en.wikipedia.org/wiki/Folk_religion] | [TOKENS: 3847] |
Contents Folk religion Folk religion, traditional religion, or vernacular religion comprises, according to religious studies and folkloristics, various forms and expressions of religion that are distinct from the doctrines and practices of organized religion. The precise definition of folk religion varies among scholars. Sometimes also termed popular belief, it consists of ethnic or regional religious customs under the umbrella of a religion; but outside doctrine and practices. The term "folk religion" is generally held to encompass two related but separate subjects. The first is the religious dimension of folk culture (folklore), or the folk-cultural dimensions of religion. The second refers to the study of religious syncretism between two cultures with different stages of formal expression, such as the melange of African folk beliefs and Roman Catholicism that led to the development of Vodun and Santería, and similar mixtures of formal religions with folk cultures. In China, folk Protestantism had its origins with the Taiping Rebellion. Chinese folk religion, folk Hinduism, folk Christianity, and folk Islam are examples of folk religion associated with major religions. The term is also used, especially by the clergy of the faiths involved, to describe the desire of people who otherwise infrequently attend religious worship, do not belong to a church or similar religious society, and who have not made a formal profession of faith in a particular creed, to have religious weddings or funerals, or (among Christians) to have their children baptised. Definition In The Concise Oxford Dictionary of World Religions, John Bowker characterized "folk religion" as either "religion which occurs in small, local communities which does not adhere to the norms of large systems" or "the appropriation of religious beliefs and practices at a popular level." Folk religion is sometimes termed "diffused religion," or "popular religion.": 83 Don Yoder argued that there were five separate ways of defining folk religion. The first was a perspective rooted in a cultural evolutionary framework which understood folk religion as representing the survivals of older forms of religion; in this, it would constitute "the survivals, in an official religious context, of beliefs and behaviour inherited from earlier stages of the culture's development". This definition would view folk religion in Catholic Europe as the survivals of pre-Christian religion and the folk religion in Protestant Europe as the survivals of Medieval Catholicism. The second definition identified by Yoder was the view that folk religion represented the mixture of an official religion with forms of ethnic religion; this was employed to explain the place of folk religion in the syncretic belief systems of the Americas, where Christianity had blended with the religions of indigenous American and African communities. Yoder's third definition was that often employed within folkloristics, which held that folk religion was "the interaction of belief, ritual, custom, and mythology in traditional societies", representing that which was often pejoratively characterised as superstition. The fourth definition provided by Yoder stated that folk religion represented the "folk interpretation and expression of religion". Noting that this definition would not encompass beliefs that were largely unconnected from organised religion, such as in witchcraft, he therefore altered this definition by including the concept of "folk religiosity", thereby defining folk religion as "the deposit in culture of folk religiosity, the full range of folk attitudes to religion". His fifth and final definition represented a "practical working definition" that combined elements from these various other definitions. Thus, he summarized folk religion as "the totality of all those views and practices of religion that exist among the people apart from and alongside the strictly theological and liturgical forms of the official religion". Yoder described "folk religion" as existing "in a complex society in relation to and in tension with the organized religion(s) of that society. Its relatively unorganized character differentiates it from organized religion". Alternately, the sociologist of religion Matthias Zic Varul defined "folk religion" as "the relatively un-reflected aspect of ordinary practices and beliefs that are oriented towards, or productive of, something beyond the immediate here-and-now: everyday transcendence". Folk religion is typically not highly institutionalized.: 84 Its practitioners typically do not form religious communities independent of the broader social communities.: 83 In sociology, folk religion is often contrasted with elite religion. Folk religion is defined as the beliefs, practices, rituals and symbols originating from sources other than the religion's leadership. Folk religion in many instances is tolerated by the religion's leadership, although they may consider it an error. A similar concept is lived religion, the study of religion as practiced by believers. The term folk religion came to be increasingly rejected in the 1990s and 2000s by scholars seeking more precise terminology. Yoder noted that one problem with the use of the term folk religion was that it did not fit into the work of those scholars who used the term "religion" in reference solely to organized religion. He highlighted the example of the prominent sociologist of religion Émile Durkheim, who insisted that religion was organized in order to contrast it with magic. Yoder noted that scholars adopting these perspectives often preferred the term "folk belief" over "folk religion". A second problem with the use of the term folk religion that Yoder highlighted was that some scholars, particularly those operating in the sociology of religion, used the term as a synonym for ethnic religion (which is alternately known as national religion or tribal religion), meaning a religion closely tied to a particular ethnic or national group and is thus contrasted with a "universal religion" which cuts across ethnic and national boundaries. Among the scholars to have adopted this use of terminology are E. Wilbur Bock. The folklorist Leonard Norman Primiano argued that the use of the term folk religion, as well as related terms like "popular religion" and "unofficial religion", by scholars, does an extreme disservice to the forms of religiosity that scholars are examining, because – in his opinion – such terms are "residualistic, [and] derogatory". He argued that using such terminology implies that there is "a pure element" to religion "which is in some way transformed, even contaminated, by its exposure to human communities". As a corrective, he suggested that scholars use "vernacular religion" as an alternative. Defining this term, Primiano stated that "vernacular religion" is, "by definition, religion as it is lived: as human beings encounter, understand, interpret, and practice it. Since religion inherently involves interpretation, it is impossible for the religion of an individual not to be vernacular". Kapaló was critical of this approach, deeming it mistaken and arguing that switching from "folk religion" to "vernacular religion" results in the scholar "picking up a different selection of things from the world". He cautioned that both terms carried an "ideological and semantic load" and warned scholars to pay attention to the associations that each word had. Historical study In Europe the study of "folk religion" emerged from the study of religiöse Volkskunde, a German term which was used in reference to "the religious dimension of folk-culture, or the folk-cultural dimension of religion". This term was first employed by a German Lutheran preacher, Paul Drews, in a 1901 article that he published which was titled "Religiöse Volkskunde, eine Aufgabe der praktischen Theologie". This article was designed to be read by young Lutheran preachers leaving the seminary, to equip them for the popular variants of Lutheranism that they would encounter among their congregations and which would differ from the official, doctrinal Lutheranism that they had been accustomed to. Although developing within a religious environment, the term came to be adopted by German academics in the field of folkloristics. During the 1920s and 1930s, theoretical studies of religiöse Volkskunde had been produced by the folklorists Josef Weigert, Werner Boette, and Max Rumpf, all of whom had focused on religiosity within German peasant communities. Over the coming decades, Georg Schreiber established an Institut für religiöse Volkskund in Munich while a similar department was established in Salzburg by Hanns Koren. Other prominent academics involved in the study of the phenomenon were Heinrich Schauert and Rudolf Kriss, the latter of whom collected one of the largest collections of folk-religious art and material culture in Europe, later housed in Munich's Bayerisches Nationalmuseum. Throughout the 20th century, many studies were made of folk religion in Europe, paying particular attention to such subjects as pilgrimage and the use of shrines. In the Americas, the study of folk religion developed among cultural anthropologists studying the syncretistic cultures of the Caribbean and Latin America. The pioneer in this field was Robert Redfield, whose 1930 book Tepoztlán: A Mexican Village contrasted and examined the relationship between "folk religion" and "official religion" in a peasant community. Yoder later noted that although the earliest known usage of the term "folk religion" in the English language was unknown, it probably developed as a translation of the German Volksreligion. One of the earliest prominent usages of the term was in the title of Joshua Trachtenberg's 1939 work Jewish Magic and Superstition: A Study in Folk Religion. The term also gained increasing usage within the academic field of comparative religion, appearing in the titles of Ichiro Hori's Folk Religion in Japan, Martin P. Nilsson's Greek Folk Religion, and Charles Leslie's reader, the Anthropology of Folk Religion. Courses on the study of folk religion came to be taught at various universities in the United States, such as John Messenger's at Indiana University and Don Yoder's at the University of Pennsylvania. Although the subject of folk religion fell within the remit of scholars operating in both folkloristics and religious studies, by 1974 Yoder noted that U.S.-based academics in the latter continued to largely ignore it, instead focusing on the study of theology and institutionalised religion; he contrasted this with the situation in Europe, where historians of religion had devoted much time to studying folk religiosity. He also lamented that many U.S.-based folklorists also neglected the subject of religion because it did not fit within the standard genre-based system for cataloguing folklore. Chinese folk religion Chinese folk religion is one of the labels used to describe the collection of ethnic religious traditions which have historically comprised the predominant belief system in China and among Han Chinese ethnic groups up to the present day. The devotion includes the veneration of the dead (ancestor worship) and of forces of nature, exorcism of demonic forces, and a belief in the rational order of nature, balance in the universe and reality that can be influenced by human beings and their rulers, as well as spirits and gods. Worship is devoted to a hierarchy of gods and immortals (Chinese: 神; pinyin: shén), who can be deities of phenomena, of human behaviour, or progenitors of lineages. Stories regarding some of these gods are collected into the body of Chinese mythology. By the 11th century (Song period), these practices had been blended with Buddhist ideas of karma (one's own doing) and rebirth, and Taoist teachings about hierarchies of deities, to form the popular religious system which has lasted in many ways until the present day. Chinese folk religion is sometimes categorized with Taoism, since over the centuries institutional Taoism has been attempting to assimilate or administer local religions. More accurately, Taoism emerged from and overlaps with folk religion and Chinese philosophy. Chinese folk religion is sometimes seen as a constituent part of Chinese traditional religion, but more often, the two are regarded as synonymous. With around 454 million adherents, or about 6.6% of the world population, Chinese folk religion is one of the major religious traditions in the world. In the People's Republic of China, more than 30% of the population follows Chinese popular religion or Taoism. Despite being heavily suppressed during the last two centuries, from the Taiping Rebellion to the Cultural Revolution, it is currently experiencing a modern revival in both Mainland China and Taiwan. Various forms have received support by the Government of the People's Republic of China, such as Mazuism in Southern China (officially about 160 million Chinese people are worshippers of Mazu), Huangdi worship, Black Dragon worship in Shaanxi, and Cai Shen worship. The term Shenism was first published by AJA Elliot in 1955 to describe Chinese folk religion in Southeast Asia. Folk Judaism In one of the first major academic works on the subject, Joshua Trachtenberg, in Jewish Magic and Superstition: A Study in Folk Religion, defined Jewish folk religion as consisting of ideas and practices that, whilst not meeting with the approval of religious leaders, enjoyed wide popularity such that they must be included in what he termed the "field of religion". This included unorthodox beliefs about demons and angels and magical practices. Later studies have emphasized the significance of the destruction of the Temple in Jerusalem to the many Jewish folk customs linked to mourning and, in particular, to the belief in hibbut ha-qever (torture of the grave): a belief that the dead are tortured in their grave for three days after burial by demons until they remember their names. This idea began with early eschatological aggadot (אגדות, 'legends', 'narratives') and was further developed by the Kabbalists. Raphael Patai is recognized as an early adopter of anthropology in studying Jewish folk religion. In particular, he was drawn to the female divine element, which he noted in the goddess Asherah, the Shekhinah, the Matronit, and Lilith. Writer Stephen Sharot has noted that Jewish folk religion, similar to other forms of folk religion, focuses on apotropaic and thaumaturgical practices intended to protect individuals from sickness and misfortune. He highlights the distinction between Rabbinic Judaism, which adheres to orthodox practice, life, and Halakha, and the unorthodox magical rituals practitioners employ in everyday life. An example mentioned is the relatively professionalized magician known as the Baal Shem (בַּעַל שֵׁם; pl. Baalei Shem) in Poland. Beginning in the 16th century and gaining prominence alongside Practical Kabbalah in the 18th century, Ba'alei Shem utilized their knowledge of the names of God and angels, along with various practices such as exorcism, chiromancy, and herbal medicine to assist individuals in achieving success in social areas like marriage and childbirth, and to bring harm to adversaries. Charles Liebman has written that the essence of the folk religion of American Jews is their social ties to one another, illustrated by the finding that religious practices that would prevent social integration—such as a strict interpretation of Kashrut and Shabbat—have been abandoned, whilst the practices that are followed—such as the Passover Seder, social rites of passage like the b'nei mitzvah, and the High Holy Days—are ones that strengthen Jewish family and community integration. Liebman described the rituals and beliefs of contemporary Jewish folk religion in his works, The Ambivalent American Jew (1973) and American Jewry: Identity and Affiliation. Folk Christianity Folk Christianity is defined differently by various scholars. Christianity as most people live it – a term used to "overcome the division of beliefs into mainstream and heterodox". Christianity as impacted by superstition as practiced by certain geographical Christian groups, and Christianity defined "in cultural terms without reference to the theologies and histories." Folk Islam Folk Islam is an umbrella term used to collectively describe forms of Islam that incorporate native folk beliefs and practices. Folk Islam has been described as the Islam of the "urban poor, country people, and tribes", in contrast to orthodox or "high" Islam (Gellner, 1992). Sufi concepts, which are found in orthodox Islam as well, and perennialism and syncretism are often integrated into Folk Islam. Folk Hinduism June McDaniel (2007) classifies Hinduism into six major kinds and numerous minor kinds, in order to understand the expression of emotions among the Hindus. According to McDaniel, one of the major kinds is Folk Hinduism, based on local ethnic traditions and cults of local deities and is the oldest, non-literate system of Indian religions. Folk Hinduism involves worship of deities which are not found in Hindu scriptures. It involves worship of Gramadevata (village deity), Kuladevata (household deity) and local deities. It is a folk religion, polytheist and animistic belief based on locality. These religions have their own priests, who worship regional deities. During the 19th century, scholars had divided Hinduism and Brahmanism. Brahmanism was referred to as an intellectual, classical tradition based on Sanskrit scriptures, while Hinduism was associated with superstitious folk tradition. The folk tradition refers to the aspects of the Hindu tradition that exist in tension with the Sanskritic tradition based on textual authority. According to M. N. Srinivas (1976), folk Hinduism is relevant in the urban context, but it is neglected in ethnographic studies due to its negative connotations with folk (rural masses, illiterate). According to Chris Fuller (1994), popular Hinduism is not degenerate textual Hinduism in light of ethnographic evidence, although the category of folk Hinduism remains tenuous. According to Michael Witzel (1998), the folk religion is the religion of Prakrit speaking and Dravidian speaking lower caste while the Vedic Hinduism which comprises Vedas and Upanishads is the religion of Sanskrit speaking upper caste. According to Asko Parpola (2015), the folk village Hinduism is surviving from pre-rig vedic Indo-Aryan times and the Indus Valley Civilization culture. Indigenous Philippine folk religions Indigenous Philippine folk religions are the distinct native religions of various ethnic groups in the Philippines, where most follow belief systems in line with animism. Generally, these indigenous folk religions are referred to as Anitism or Bathalism. Some of these beliefs stem from pre-Christian religions that were especially influenced by Hinduism and were regarded by the Spanish as "myths" and "superstitions" in an effort to de-legitimize legitimate precolonial beliefs by forcefully replacing those native beliefs with Catholic Christian beliefs. Today, some of these precolonial beliefs are still held by Filipinos, especially in the provinces. See also References Further reading |
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[SOURCE: https://en.wikipedia.org/wiki/Lod#cite_ref-EB_33-1] | [TOKENS: 4733] |
Contents Lod Lod (Hebrew: לוד, fully vocalized: לֹד), also known as Lydda (Ancient Greek: Λύδδα) and Lidd (Arabic: اللِّدّ, romanized: al-Lidd, or اللُّدّ, al-Ludd), is a city 15 km (9+1⁄2 mi) southeast of Tel Aviv and 40 km (25 mi) northwest of Jerusalem in the Central District of Israel. It is situated between the lower Shephelah on the east and the coastal plain on the west. The city had a population of 90,814 in 2023. Lod has been inhabited since at least the Neolithic period. It is mentioned a few times in the Hebrew Bible and in the New Testament. Between the 5th century BCE and up until the late Roman period, it was a prominent center for Jewish scholarship and trade. Around 200 CE, the city became a Roman colony and was renamed Diospolis (Ancient Greek: Διόσπολις, lit. 'city of Zeus'). Tradition identifies Lod as the 4th century martyrdom site of Saint George; the Church of Saint George and Mosque of Al-Khadr located in the city is believed to have housed his remains. Following the Arab conquest of the Levant, Lod served as the capital of Jund Filastin; however, a few decades later, the seat of power was transferred to Ramla, and Lod slipped in importance. Under Crusader rule, the city was a Catholic diocese of the Latin Church and it remains a titular see to this day.[citation needed] Lod underwent a major change in its population in the mid-20th century. Exclusively Palestinian Arab in 1947, Lod was part of the area designated for an Arab state in the United Nations Partition Plan for Palestine; however, in July 1948, the city was occupied by the Israel Defense Forces, and most of its Arab inhabitants were expelled in the Palestinian expulsion from Lydda and Ramle. The city was largely resettled by Jewish immigrants, most of them expelled from Arab countries. Today, Lod is one of Israel's mixed cities, with an Arab population of 30%. Lod is one of Israel's major transportation hubs. The main international airport, Ben Gurion Airport, is located 8 km (5 miles) north of the city. The city is also a major railway and road junction. Religious references The Hebrew name Lod appears in the Hebrew Bible as a town of Benjamin, founded along with Ono by Shamed or Shamer (1 Chronicles 8:12; Ezra 2:33; Nehemiah 7:37; 11:35). In Ezra 2:33, it is mentioned as one of the cities whose inhabitants returned after the Babylonian captivity. Lod is not mentioned among the towns allocated to the tribe of Benjamin in Joshua 18:11–28. The name Lod derives from a tri-consonantal root not extant in Northwest Semitic, but only in Arabic (“to quarrel; withhold, hinder”). An Arabic etymology of such an ancient name is unlikely (the earliest attestation is from the Achaemenid period). In the New Testament, the town appears in its Greek form, Lydda, as the site of Peter's healing of Aeneas in Acts 9:32–38. The city is also mentioned in an Islamic hadith as the location of the battlefield where the false messiah (al-Masih ad-Dajjal) will be slain before the Day of Judgment. History The first occupation dates to the Neolithic in the Near East and is associated with the Lodian culture. Occupation continued in the Levant Chalcolithic. Pottery finds have dated the initial settlement in the area now occupied by the town to 5600–5250 BCE. In the Early Bronze, it was an important settlement in the central coastal plain between the Judean Shephelah and the Mediterranean coast, along Nahal Ayalon. Other important nearby sites were Tel Dalit, Tel Bareqet, Khirbat Abu Hamid (Shoham North), Tel Afeq, Azor and Jaffa. Two architectural phases belong to the late EB I in Area B. The first phase had a mudbrick wall, while the late phase included a circulat stone structure. Later excavations have produced an occupation later, Stratum IV. It consists of two phases, Stratum IVb with mudbrick wall on stone foundations and rounded exterior corners. In Stratum IVa there was a mudbrick wall with no stone foundations, with imported Egyptian potter and local pottery imitations. Another excavations revealed nine occupation strata. Strata VI-III belonged to Early Bronze IB. The material culture showed Egyptian imports in strata V and IV. Occupation continued into Early Bronze II with four strata (V-II). There was continuity in the material culture and indications of centralized urban planning. North to the tell were scattered MB II burials. The earliest written record is in a list of Canaanite towns drawn up by the Egyptian pharaoh Thutmose III at Karnak in 1465 BCE. From the fifth century BCE until the Roman period, the city was a centre of Jewish scholarship and commerce. According to British historian Martin Gilbert, during the Hasmonean period, Jonathan Maccabee and his brother, Simon Maccabaeus, enlarged the area under Jewish control, which included conquering the city. The Jewish community in Lod during the Mishnah and Talmud era is described in a significant number of sources, including information on its institutions, demographics, and way of life. The city reached its height as a Jewish center between the First Jewish-Roman War and the Bar Kokhba revolt, and again in the days of Judah ha-Nasi and the start of the Amoraim period. The city was then the site of numerous public institutions, including schools, study houses, and synagogues. In 43 BC, Cassius, the Roman governor of Syria, sold the inhabitants of Lod into slavery, but they were set free two years later by Mark Antony. During the First Jewish–Roman War, the Roman proconsul of Syria, Cestius Gallus, razed the town on his way to Jerusalem in Tishrei 66 CE. According to Josephus, "[he] found the city deserted, for the entire population had gone up to Jerusalem for the Feast of Tabernacles. He killed fifty people whom he found, burned the town and marched on". Lydda was occupied by Emperor Vespasian in 68 CE. In the period following the destruction of Jerusalem in 70 CE, Rabbi Tarfon, who appears in many Tannaitic and Jewish legal discussions, served as a rabbinic authority in Lod. During the Kitos War, 115–117 CE, the Roman army laid siege to Lod, where the rebel Jews had gathered under the leadership of Julian and Pappos. Torah study was outlawed by the Romans and pursued mostly in the underground. The distress became so great, the patriarch Rabban Gamaliel II, who was shut up there and died soon afterwards, permitted fasting on Ḥanukkah. Other rabbis disagreed with this ruling. Lydda was next taken and many of the Jews were executed; the "slain of Lydda" are often mentioned in words of reverential praise in the Talmud. In 200 CE, emperor Septimius Severus elevated the town to the status of a city, calling it Colonia Lucia Septimia Severa Diospolis. The name Diospolis ("City of Zeus") may have been bestowed earlier, possibly by Hadrian. At that point, most of its inhabitants were Christian. The earliest known bishop is Aëtius, a friend of Arius. During the following century (200-300CE), it's said that Joshua ben Levi founded a yeshiva in Lod. In December 415, the Council of Diospolis was held here to try Pelagius; he was acquitted. In the sixth century, the city was renamed Georgiopolis after St. George, a soldier in the guard of the emperor Diocletian, who was born there between 256 and 285 CE. The Church of Saint George and Mosque of Al-Khadr is named for him. The 6th-century Madaba map shows Lydda as an unwalled city with a cluster of buildings under a black inscription reading "Lod, also Lydea, also Diospolis". An isolated large building with a semicircular colonnaded plaza in front of it might represent the St George shrine. After the Muslim conquest of Palestine by Amr ibn al-'As in 636 CE, Lod which was referred to as "al-Ludd" in Arabic served as the capital of Jund Filastin ("Military District of Palaestina") before the seat of power was moved to nearby Ramla during the reign of the Umayyad Caliph Suleiman ibn Abd al-Malik in 715–716. The population of al-Ludd was relocated to Ramla, as well. With the relocation of its inhabitants and the construction of the White Mosque in Ramla, al-Ludd lost its importance and fell into decay. The city was visited by the local Arab geographer al-Muqaddasi in 985, when it was under the Fatimid Caliphate, and was noted for its Great Mosque which served the residents of al-Ludd, Ramla, and the nearby villages. He also wrote of the city's "wonderful church (of St. George) at the gate of which Christ will slay the Antichrist." The Crusaders occupied the city in 1099 and named it St Jorge de Lidde. It was briefly conquered by Saladin, but retaken by the Crusaders in 1191. For the English Crusaders, it was a place of great significance as the birthplace of Saint George. The Crusaders made it the seat of a Latin Church diocese, and it remains a titular see. It owed the service of 10 knights and 20 sergeants, and it had its own burgess court during this era. In 1226, Ayyubid Syrian geographer Yaqut al-Hamawi visited al-Ludd and stated it was part of the Jerusalem District during Ayyubid rule. Sultan Baybars brought Lydda again under Muslim control by 1267–8. According to Qalqashandi, Lydda was an administrative centre of a wilaya during the fourteenth and fifteenth century in the Mamluk empire. Mujir al-Din described it as a pleasant village with an active Friday mosque. During this time, Lydda was a station on the postal route between Cairo and Damascus. In 1517, Lydda was incorporated into the Ottoman Empire as part of the Damascus Eyalet, and in the 1550s, the revenues of Lydda were designated for the new waqf of Hasseki Sultan Imaret in Jerusalem, established by Hasseki Hurrem Sultan (Roxelana), the wife of Suleiman the Magnificent. By 1596 Lydda was a part of the nahiya ("subdistrict") of Ramla, which was under the administration of the liwa ("district") of Gaza. It had a population of 241 households and 14 bachelors who were all Muslims, and 233 households who were Christians. They paid a fixed tax-rate of 33,3 % on agricultural products, including wheat, barley, summer crops, vineyards, fruit trees, sesame, special product ("dawalib" =spinning wheels), goats and beehives, in addition to occasional revenues and market toll, a total of 45,000 Akçe. All of the revenue went to the Waqf. In 1051 AH/1641/2, the Bedouin tribe of al-Sawālima from around Jaffa attacked the villages of Subṭāra, Bayt Dajan, al-Sāfiriya, Jindās, Lydda and Yāzūr belonging to Waqf Haseki Sultan. The village appeared as Lydda, though misplaced, on the map of Pierre Jacotin compiled in 1799. Missionary William M. Thomson visited Lydda in the mid-19th century, describing it as a "flourishing village of some 2,000 inhabitants, imbosomed in noble orchards of olive, fig, pomegranate, mulberry, sycamore, and other trees, surrounded every way by a very fertile neighbourhood. The inhabitants are evidently industrious and thriving, and the whole country between this and Ramleh is fast being filled up with their flourishing orchards. Rarely have I beheld a rural scene more delightful than this presented in early harvest ... It must be seen, heard, and enjoyed to be appreciated." In 1869, the population of Ludd was given as: 55 Catholics, 1,940 "Greeks", 5 Protestants and 4,850 Muslims. In 1870, the Church of Saint George was rebuilt. In 1892, the first railway station in the entire region was established in the city. In the second half of the 19th century, Jewish merchants migrated to the city, but left after the 1921 Jaffa riots. In 1882, the Palestine Exploration Fund's Survey of Western Palestine described Lod as "A small town, standing among enclosure of prickly pear, and having fine olive groves around it, especially to the south. The minaret of the mosque is a very conspicuous object over the whole of the plain. The inhabitants are principally Moslim, though the place is the seat of a Greek bishop resident of Jerusalem. The Crusading church has lately been restored, and is used by the Greeks. Wells are found in the gardens...." From 1918, Lydda was under the administration of the British Mandate in Palestine, as per a League of Nations decree that followed the Great War. During the Second World War, the British set up supply posts in and around Lydda and its railway station, also building an airport that was renamed Ben Gurion Airport after the death of Israel's first prime minister in 1973. At the time of the 1922 census of Palestine, Lydda had a population of 8,103 inhabitants (7,166 Muslims, 926 Christians, and 11 Jews), the Christians were 921 Orthodox, 4 Roman Catholics and 1 Melkite. This had increased by the 1931 census to 11,250 (10,002 Muslims, 1,210 Christians, 28 Jews, and 10 Bahai), in a total of 2475 residential houses. In 1938, Lydda had a population of 12,750. In 1945, Lydda had a population of 16,780 (14,910 Muslims, 1,840 Christians, 20 Jews and 10 "other"). Until 1948, Lydda was an Arab town with a population of around 20,000—18,500 Muslims and 1,500 Christians. In 1947, the United Nations proposed dividing Mandatory Palestine into two states, one Jewish state and one Arab; Lydda was to form part of the proposed Arab state. In the ensuing war, Israel captured Arab towns outside the area the UN had allotted it, including Lydda. In December 1947, thirteen Jewish passengers in a seven-car convoy to Ben Shemen Youth Village were ambushed and murdered.In a separate incident, three Jewish youths, two men and a woman were captured, then raped and murdered in a neighbouring village. Their bodies were paraded in Lydda’s principal street. The Israel Defense Forces entered Lydda on 11 July 1948. The following day, under the impression that it was under attack, the 3rd Battalion was ordered to shoot anyone "seen on the streets". According to Israel, 250 Arabs were killed. Other estimates are higher: Arab historian Aref al Aref estimated 400, and Nimr al Khatib 1,700. In 1948, the population rose to 50,000 during the Nakba, as Arab refugees fleeing other areas made their way there. A key event was the Palestinian expulsion from Lydda and Ramle, with the expulsion of 50,000-70,000 Palestinians from Lydda and Ramle by the Israel Defense Forces. All but 700 to 1,056 were expelled by order of the Israeli high command, and forced to walk 17 km (10+1⁄2 mi) to the Jordanian Arab Legion lines. Estimates of those who died from exhaustion and dehydration vary from a handful to 355. The town was subsequently sacked by the Israeli army. Some scholars, including Ilan Pappé, characterize this as ethnic cleansing. The few hundred Arabs who remained in the city were soon outnumbered by the influx of Jews who immigrated to Lod from August 1948 onward, most of them from Arab countries. As a result, Lod became a predominantly Jewish town. After the establishment of the state, the biblical name Lod was readopted. The Jewish immigrants who settled Lod came in waves, first from Morocco and Tunisia, later from Ethiopia, and then from the former Soviet Union. Since 2008, many urban development projects have been undertaken to improve the image of the city. Upscale neighbourhoods have been built, among them Ganei Ya'ar and Ahisemah, expanding the city to the east. According to a 2010 report in the Economist, a three-meter-high wall was built between Jewish and Arab neighbourhoods and construction in Jewish areas was given priority over construction in Arab neighborhoods. The newspaper says that violent crime in the Arab sector revolves mainly around family feuds over turf and honour crimes. In 2010, the Lod Community Foundation organised an event for representatives of bicultural youth movements, volunteer aid organisations, educational start-ups, businessmen, sports organizations, and conservationists working on programmes to better the city. In the 2021 Israel–Palestine crisis, a state of emergency was declared in Lod after Arab rioting led to the death of an Israeli Jew. The Mayor of Lod, Yair Revivio, urged Prime Minister of Israel Benjamin Netanyahu to deploy Israel Border Police to restore order in the city. This was the first time since 1966 that Israel had declared this kind of emergency lockdown. International media noted that both Jewish and Palestinian mobs were active in Lod, but the "crackdown came for one side" only. Demographics In the 19th century and until the Lydda Death March, Lod was an exclusively Muslim-Christian town, with an estimated 6,850 inhabitants, of whom approximately 2,000 (29%) were Christian. According to the Israel Central Bureau of Statistics (CBS), the population of Lod in 2010 was 69,500 people. According to the 2019 census, the population of Lod was 77,223, of which 53,581 people, comprising 69.4% of the city's population, were classified as "Jews and Others", and 23,642 people, comprising 30.6% as "Arab". Education According to CBS, 38 schools and 13,188 pupils are in the city. They are spread out as 26 elementary schools and 8,325 elementary school pupils, and 13 high schools and 4,863 high school pupils. About 52.5% of 12th-grade pupils were entitled to a matriculation certificate in 2001.[citation needed] Economy The airport and related industries are a major source of employment for the residents of Lod. Other important factories in the city are the communication equipment company "Talard", "Cafe-Co" - a subsidiary of the Strauss Group and "Kashev" - the computer center of Bank Leumi. A Jewish Agency Absorption Centre is also located in Lod. According to CBS figures for 2000, 23,032 people were salaried workers and 1,405 were self-employed. The mean monthly wage for a salaried worker was NIS 4,754, a real change of 2.9% over the course of 2000. Salaried men had a mean monthly wage of NIS 5,821 (a real change of 1.4%) versus NIS 3,547 for women (a real change of 4.6%). The mean income for the self-employed was NIS 4,991. About 1,275 people were receiving unemployment benefits and 7,145 were receiving an income supplement. Art and culture In 2009-2010, Dor Guez held an exhibit, Georgeopolis, at the Petach Tikva art museum that focuses on Lod. Archaeology A well-preserved mosaic floor dating to the Roman period was excavated in 1996 as part of a salvage dig conducted on behalf of the Israel Antiquities Authority and the Municipality of Lod, prior to widening HeHalutz Street. According to Jacob Fisch, executive director of the Friends of the Israel Antiquities Authority, a worker at the construction site noticed the tail of a tiger and halted work. The mosaic was initially covered over with soil at the conclusion of the excavation for lack of funds to conserve and develop the site. The mosaic is now part of the Lod Mosaic Archaeological Center. The floor, with its colorful display of birds, fish, exotic animals and merchant ships, is believed to have been commissioned by a wealthy resident of the city for his private home. The Lod Community Archaeology Program, which operates in ten Lod schools, five Jewish and five Israeli Arab, combines archaeological studies with participation in digs in Lod. Sports The city's major football club, Hapoel Bnei Lod, plays in Liga Leumit (the second division). Its home is at the Lod Municipal Stadium. The club was formed by a merger of Bnei Lod and Rakevet Lod in the 1980s. Two other clubs in the city play in the regional leagues: Hapoel MS Ortodoxim Lod in Liga Bet and Maccabi Lod in Liga Gimel. Hapoel Lod played in the top division during the 1960s and 1980s, and won the State Cup in 1984. The club folded in 2002. A new club, Hapoel Maxim Lod (named after former mayor Maxim Levy) was established soon after, but folded in 2007. Notable people Twin towns-sister cities Lod is twinned with: See also References Bibliography External links |
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Contents Elon Musk Elon Reeve Musk (/ˈiːlɒn/ EE-lon; born June 28, 1971) is a businessman and entrepreneur known for his leadership of Tesla, SpaceX, Twitter, and xAI. Musk has been the wealthiest person in the world since 2025; as of February 2026,[update] Forbes estimates his net worth to be around US$852 billion. Born into a wealthy family in Pretoria, South Africa, Musk emigrated in 1989 to Canada; he has Canadian citizenship since his mother was born there. He received bachelor's degrees in 1997 from the University of Pennsylvania before moving to California to pursue business ventures. In 1995, Musk co-founded the software company Zip2. Following its sale in 1999, he co-founded X.com, an online payment company that later merged to form PayPal, which was acquired by eBay in 2002. Musk also became an American citizen in 2002. In 2002, Musk founded the space technology company SpaceX, becoming its CEO and chief engineer; the company has since led innovations in reusable rockets and commercial spaceflight. Musk joined the automaker Tesla as an early investor in 2004 and became its CEO and product architect in 2008; it has since become a leader in electric vehicles. In 2015, he co-founded OpenAI to advance artificial intelligence (AI) research, but later left; growing discontent with the organization's direction and their leadership in the AI boom in the 2020s led him to establish xAI, which became a subsidiary of SpaceX in 2026. In 2022, he acquired the social network Twitter, implementing significant changes, and rebranding it as X in 2023. His other businesses include the neurotechnology company Neuralink, which he co-founded in 2016, and the tunneling company the Boring Company, which he founded in 2017. In November 2025, a Tesla pay package worth $1 trillion for Musk was approved, which he is to receive over 10 years if he meets specific goals. Musk was the largest donor in the 2024 U.S. presidential election, where he supported Donald Trump. After Trump was inaugurated as president in early 2025, Musk served as Senior Advisor to the President and as the de facto head of the Department of Government Efficiency (DOGE). After a public feud with Trump, Musk left the Trump administration and returned to managing his companies. Musk is a supporter of global far-right figures, causes, and political parties. His political activities, views, and statements have made him a polarizing figure. Musk has been criticized for COVID-19 misinformation, promoting conspiracy theories, and affirming antisemitic, racist, and transphobic comments. His acquisition of Twitter was controversial due to a subsequent increase in hate speech and the spread of misinformation on the service, following his pledge to decrease censorship. His role in the second Trump administration attracted public backlash, particularly in response to DOGE. The emails he sent to Jeffrey Epstein are included in the Epstein files, which were published between 2025–26 and became a topic of worldwide debate. Early life Elon Reeve Musk was born on June 28, 1971, in Pretoria, South Africa's administrative capital. He is of British and Pennsylvania Dutch ancestry. His mother, Maye (née Haldeman), is a model and dietitian born in Saskatchewan, Canada, and raised in South Africa. Musk therefore holds both South African and Canadian citizenship from birth. His father, Errol Musk, is a South African electromechanical engineer, pilot, sailor, consultant, emerald dealer, and property developer, who partly owned a rental lodge at Timbavati Private Nature Reserve. His maternal grandfather, Joshua N. Haldeman, who died in a plane crash when Elon was a toddler, was an American-born Canadian chiropractor, aviator and political activist in the technocracy movement who moved to South Africa in 1950. Elon has a younger brother, Kimbal, a younger sister, Tosca, and four paternal half-siblings. Musk was baptized as a child in the Anglican Church of Southern Africa. Despite both Elon and Errol previously stating that Errol was a part owner of a Zambian emerald mine, in 2023, Errol recounted that the deal he made was to receive "a portion of the emeralds produced at three small mines". Errol was elected to the Pretoria City Council as a representative of the anti-apartheid Progressive Party and has said that his children shared their father's dislike of apartheid. After his parents divorced in 1979, Elon, aged around 9, chose to live with his father because Errol Musk had an Encyclopædia Britannica and a computer. Elon later regretted his decision and became estranged from his father. Elon has recounted trips to a wilderness school that he described as a "paramilitary Lord of the Flies" where "bullying was a virtue" and children were encouraged to fight over rations. In one incident, after an altercation with a fellow pupil, Elon was thrown down concrete steps and beaten severely, leading to him being hospitalized for his injuries. Elon described his father berating him after he was discharged from the hospital. Errol denied berating Elon and claimed, "The [other] boy had just lost his father to suicide, and Elon had called him stupid. Elon had a tendency to call people stupid. How could I possibly blame that child?" Elon was an enthusiastic reader of books, and had attributed his success in part to having read The Lord of the Rings, the Foundation series, and The Hitchhiker's Guide to the Galaxy. At age ten, he developed an interest in computing and video games, teaching himself how to program from the VIC-20 user manual. At age twelve, Elon sold his BASIC-based game Blastar to PC and Office Technology magazine for approximately $500 (equivalent to $1,600 in 2025). Musk attended Waterkloof House Preparatory School, Bryanston High School, and then Pretoria Boys High School, where he graduated. Musk was a decent but unexceptional student, earning a 61/100 in Afrikaans and a B on his senior math certification. Musk applied for a Canadian passport through his Canadian-born mother to avoid South Africa's mandatory military service, which would have forced him to participate in the apartheid regime, as well as to ease his path to immigration to the United States. While waiting for his application to be processed, he attended the University of Pretoria for five months. Musk arrived in Canada in June 1989, connected with a second cousin in Saskatchewan, and worked odd jobs, including at a farm and a lumber mill. In 1990, he entered Queen's University in Kingston, Ontario. Two years later, he transferred to the University of Pennsylvania, where he studied until 1995. Although Musk has said that he earned his degrees in 1995, the University of Pennsylvania did not award them until 1997 – a Bachelor of Arts in physics and a Bachelor of Science in economics from the university's Wharton School. He reportedly hosted large, ticketed house parties to help pay for tuition, and wrote a business plan for an electronic book-scanning service similar to Google Books. In 1994, Musk held two internships in Silicon Valley: one at energy storage startup Pinnacle Research Institute, which investigated electrolytic supercapacitors for energy storage, and another at Palo Alto–based startup Rocket Science Games. In 1995, he was accepted to a graduate program in materials science at Stanford University, but did not enroll. Musk decided to join the Internet boom of the 1990s, applying for a job at Netscape, to which he reportedly never received a response. The Washington Post reported that Musk lacked legal authorization to remain and work in the United States after failing to enroll at Stanford. In response, Musk said he was allowed to work at that time and that his student visa transitioned to an H1-B. According to numerous former business associates and shareholders, Musk said he was on a student visa at the time. Business career In 1995, Musk, his brother Kimbal, and Greg Kouri founded the web software company Zip2 with funding from a group of angel investors. They housed the venture at a small rented office in Palo Alto. Replying to Rolling Stone, Musk denounced the notion that they started their company with funds borrowed from Errol Musk, but in a tweet, he recognized that his father contributed 10% of a later funding round. The company developed and marketed an Internet city guide for the newspaper publishing industry, with maps, directions, and yellow pages. According to Musk, "The website was up during the day and I was coding it at night, seven days a week, all the time." To impress investors, Musk built a large plastic structure around a standard computer to create the impression that Zip2 was powered by a small supercomputer. The Musk brothers obtained contracts with The New York Times and the Chicago Tribune, and persuaded the board of directors to abandon plans for a merger with CitySearch. Musk's attempts to become CEO were thwarted by the board. Compaq acquired Zip2 for $307 million in cash in February 1999 (equivalent to $590,000,000 in 2025), and Musk received $22 million (equivalent to $43,000,000 in 2025) for his 7-percent share. In 1999, Musk co-founded X.com, an online financial services and e-mail payment company. The startup was one of the first federally insured online banks, and, in its initial months of operation, over 200,000 customers joined the service. The company's investors regarded Musk as inexperienced and replaced him with Intuit CEO Bill Harris by the end of the year. The following year, X.com merged with online bank Confinity to avoid competition. Founded by Max Levchin and Peter Thiel, Confinity had its own money-transfer service, PayPal, which was more popular than X.com's service. Within the merged company, Musk returned as CEO. Musk's preference for Microsoft software over Unix created a rift in the company and caused Thiel to resign. Due to resulting technological issues and lack of a cohesive business model, the board ousted Musk and replaced him with Thiel in 2000.[b] Under Thiel, the company focused on the PayPal service and was renamed PayPal in 2001. In 2002, PayPal was acquired by eBay for $1.5 billion (equivalent to $2,700,000,000 in 2025) in stock, of which Musk—the largest shareholder with 11.72% of shares—received $175.8 million (equivalent to $320,000,000 in 2025). In 2017, Musk purchased the domain X.com from PayPal for an undisclosed amount, stating that it had sentimental value. In 2001, Musk became involved with the nonprofit Mars Society and discussed funding plans to place a growth-chamber for plants on Mars. Seeking a way to launch the greenhouse payloads into space, Musk made two unsuccessful trips to Moscow to purchase intercontinental ballistic missiles (ICBMs) from Russian companies NPO Lavochkin and Kosmotras. Musk instead decided to start a company to build affordable rockets. With $100 million of his early fortune, (equivalent to $180,000,000 in 2025) Musk founded SpaceX in May 2002 and became the company's CEO and Chief Engineer. SpaceX attempted its first launch of the Falcon 1 rocket in 2006. Although the rocket failed to reach Earth orbit, it was awarded a Commercial Orbital Transportation Services program contract from NASA, then led by Mike Griffin. After two more failed attempts that nearly caused Musk to go bankrupt, SpaceX succeeded in launching the Falcon 1 into orbit in 2008. Later that year, SpaceX received a $1.6 billion NASA contract (equivalent to $2,400,000,000 in 2025) for Falcon 9-launched Dragon spacecraft flights to the International Space Station (ISS), replacing the Space Shuttle after its 2011 retirement. In 2012, the Dragon vehicle docked with the ISS, a first for a commercial spacecraft. Working towards its goal of reusable rockets, in 2015 SpaceX successfully landed the first stage of a Falcon 9 on a land platform. Later landings were achieved on autonomous spaceport drone ships, an ocean-based recovery platform. In 2018, SpaceX launched the Falcon Heavy; the inaugural mission carried Musk's personal Tesla Roadster as a dummy payload. Since 2019, SpaceX has been developing Starship, a reusable, super heavy-lift launch vehicle intended to replace the Falcon 9 and Falcon Heavy. In 2020, SpaceX launched its first crewed flight, the Demo-2, becoming the first private company to place astronauts into orbit and dock a crewed spacecraft with the ISS. In 2024, NASA awarded SpaceX an $843 million (equivalent to $865,000,000 in 2025) contract to build a spacecraft that NASA will use to deorbit the ISS at the end of its lifespan. In 2015, SpaceX began development of the Starlink constellation of low Earth orbit satellites to provide satellite Internet access. After the launch of prototype satellites in 2018, the first large constellation was deployed in May 2019. As of May 2025[update], over 7,600 Starlink satellites are operational, comprising 65% of all operational Earth satellites. The total cost of the decade-long project to design, build, and deploy the constellation was estimated by SpaceX in 2020 to be $10 billion (equivalent to $12,000,000,000 in 2025).[c] During the Russian invasion of Ukraine, Musk provided free Starlink service to Ukraine, permitting Internet access and communication at a yearly cost to SpaceX of $400 million (equivalent to $440,000,000 in 2025). However, Musk refused to block Russian state media on Starlink. In 2023, Musk denied Ukraine's request to activate Starlink over Crimea to aid an attack against the Russian navy, citing fears of a nuclear response. Tesla, Inc., originally Tesla Motors, was incorporated in July 2003 by Martin Eberhard and Marc Tarpenning. Both men played active roles in the company's early development prior to Musk's involvement. Musk led the Series A round of investment in February 2004; he invested $6.35 million (equivalent to $11,000,000 in 2025), became the majority shareholder, and joined Tesla's board of directors as chairman. Musk took an active role within the company and oversaw Roadster product design, but was not deeply involved in day-to-day business operations. Following a series of escalating conflicts in 2007 and the 2008 financial crisis, Eberhard was ousted from the firm.[page needed] Musk assumed leadership of the company as CEO and product architect in 2008. A 2009 lawsuit settlement with Eberhard designated Musk as a Tesla co-founder, along with Tarpenning and two others. Tesla began delivery of the Roadster, an electric sports car, in 2008. With sales of about 2,500 vehicles, it was the first mass production all-electric car to use lithium-ion battery cells. Under Musk, Tesla has since launched several well-selling electric vehicles, including the four-door sedan Model S (2012), the crossover Model X (2015), the mass-market sedan Model 3 (2017), the crossover Model Y (2020), and the pickup truck Cybertruck (2023). In May 2020, Musk resigned as chairman of the board as part of the settlement of a lawsuit from the SEC over him tweeting that funding had been "secured" for potentially taking Tesla private. The company has also constructed multiple lithium-ion battery and electric vehicle factories, called Gigafactories. Since its initial public offering in 2010, Tesla stock has risen significantly; it became the most valuable carmaker in summer 2020, and it entered the S&P 500 later that year. In October 2021, it reached a market capitalization of $1 trillion (equivalent to $1,200,000,000,000 in 2025), the sixth company in U.S. history to do so. Musk provided the initial concept and financial capital for SolarCity, which his cousins Lyndon and Peter Rive founded in 2006. By 2013, SolarCity was the second largest provider of solar power systems in the United States. In 2014, Musk promoted the idea of SolarCity building an advanced production facility in Buffalo, New York, triple the size of the largest solar plant in the United States. Construction of the factory started in 2014 and was completed in 2017. It operated as a joint venture with Panasonic until early 2020. Tesla acquired SolarCity for $2 billion in 2016 (equivalent to $2,700,000,000 in 2025) and merged it with its battery unit to create Tesla Energy. The deal's announcement resulted in a more than 10% drop in Tesla's stock price; at the time, SolarCity was facing liquidity issues. Multiple shareholder groups filed a lawsuit against Musk and Tesla's directors, stating that the purchase of SolarCity was done solely to benefit Musk and came at the expense of Tesla and its shareholders. Tesla directors settled the lawsuit in January 2020, leaving Musk the sole remaining defendant. Two years later, the court ruled in Musk's favor. In 2016, Musk co-founded Neuralink, a neurotechnology startup, with an investment of $100 million. Neuralink aims to integrate the human brain with artificial intelligence (AI) by creating devices that are embedded in the brain. Such technology could enhance memory or allow the devices to communicate with software. The company also hopes to develop devices to treat neurological conditions like spinal cord injuries. In 2022, Neuralink announced that clinical trials would begin by the end of the year. In September 2023, the Food and Drug Administration approved Neuralink to initiate six-year human trials. Neuralink has conducted animal testing on macaques at the University of California, Davis. In 2021, the company released a video in which a macaque played the video game Pong via a Neuralink implant. The company's animal trials—which have caused the deaths of some monkeys—have led to claims of animal cruelty. The Physicians Committee for Responsible Medicine has alleged that Neuralink violated the Animal Welfare Act. Employees have complained that pressure from Musk to accelerate development has led to botched experiments and unnecessary animal deaths. In 2022, a federal probe was launched into possible animal welfare violations by Neuralink.[needs update] In 2017, Musk founded the Boring Company to construct tunnels; he also revealed plans for specialized, underground, high-occupancy vehicles that could travel up to 150 miles per hour (240 km/h) and thus circumvent above-ground traffic in major cities. Early in 2017, the company began discussions with regulatory bodies and initiated construction of a 30-foot (9.1 m) wide, 50-foot (15 m) long, and 15-foot (4.6 m) deep "test trench" on the premises of SpaceX's offices, as that required no permits. The Los Angeles tunnel, less than two miles (3.2 km) in length, debuted to journalists in 2018. It used Tesla Model Xs and was reported to be a rough ride while traveling at suboptimal speeds. Two tunnel projects announced in 2018, in Chicago and West Los Angeles, have been canceled. A tunnel beneath the Las Vegas Convention Center was completed in early 2021. Local officials have approved further expansions of the tunnel system. April 14, 2022 In early 2017, Musk expressed interest in buying Twitter and had questioned the platform's commitment to freedom of speech. By 2022, Musk had reached 9.2% stake in the company, making him the largest shareholder.[d] Musk later agreed to a deal that would appoint him to Twitter's board of directors and prohibit him from acquiring more than 14.9% of the company. Days later, Musk made a $43 billion offer to buy Twitter. By the end of April Musk had successfully concluded his bid for approximately $44 billion. This included approximately $12.5 billion in loans and $21 billion in equity financing. Having backtracked on his initial decision, Musk bought the company on October 27, 2022. Immediately after the acquisition, Musk fired several top Twitter executives including CEO Parag Agrawal; Musk became the CEO instead. Under Elon Musk, Twitter instituted monthly subscriptions for a "blue check", and laid off a significant portion of the company's staff. Musk lessened content moderation and hate speech also increased on the platform after his takeover. In late 2022, Musk released internal documents relating to Twitter's moderation of Hunter Biden's laptop controversy in the lead-up to the 2020 presidential election. Musk also promised to step down as CEO after a Twitter poll, and five months later, Musk stepped down as CEO and transitioned his role to executive chairman and chief technology officer (CTO). Despite Musk stepping down as CEO, X continues to struggle with challenges such as viral misinformation, hate speech, and antisemitism controversies. Musk has been accused of trying to silence some of his critics such as Twitch streamer Asmongold, who criticized him during one of his streams. Musk has been accused of removing their accounts' blue checkmarks, which hinders visibility and is considered a form of shadow banning, or suspending their accounts without justification. Other activities In August 2013, Musk announced plans for a version of a vactrain, and assigned engineers from SpaceX and Tesla to design a transport system between Greater Los Angeles and the San Francisco Bay Area, at an estimated cost of $6 billion. Later that year, Musk unveiled the concept, dubbed the Hyperloop, intended to make travel cheaper than any other mode of transport for such long distances. In December 2015, Musk co-founded OpenAI, a not-for-profit artificial intelligence (AI) research company aiming to develop artificial general intelligence, intended to be safe and beneficial to humanity. Musk pledged $1 billion of funding to the company, and initially gave $50 million. In 2018, Musk left the OpenAI board. Since 2018, OpenAI has made significant advances in machine learning. In July 2023, Musk launched the artificial intelligence company xAI, which aims to develop a generative AI program that competes with existing offerings like OpenAI's ChatGPT. Musk obtained funding from investors in SpaceX and Tesla, and xAI hired engineers from Google and OpenAI. December 16, 2022 Musk uses a private jet owned by Falcon Landing LLC, a SpaceX-linked company, and acquired a second jet in August 2020. His heavy use of the jets and the consequent fossil fuel usage have received criticism. Musk's flight usage is tracked on social media through ElonJet. In December 2022, Musk banned the ElonJet account on Twitter, and made temporary bans on the accounts of journalists that posted stories regarding the incident, including Donie O'Sullivan, Keith Olbermann, and journalists from The New York Times, The Washington Post, CNN, and The Intercept. In October 2025, Musk's company xAI launched Grokipedia, an AI-generated online encyclopedia that he promoted as an alternative to Wikipedia. Articles on Grokipedia are generated and reviewed by xAI's Grok chatbot. Media coverage and academic analysis described Grokipedia as frequently reusing Wikipedia content but framing contested political and social topics in line with Musk's own views and right-wing narratives. A study by Cornell University researchers and NBC News stated that Grokipedia cites sources that are blacklisted or considered "generally unreliable" on Wikipedia, for example, the conspiracy site Infowars and the neo-Nazi forum Stormfront. Wired, The Guardian and Time criticized Grokipedia for factual errors and for presenting Musk himself in unusually positive terms while downplaying controversies. Politics Musk is an outlier among business leaders who typically avoid partisan political advocacy. Musk was a registered independent voter when he lived in California. Historically, he has donated to both Democrats and Republicans, many of whom serve in states in which he has a vested interest. Since 2022, his political contributions have mostly supported Republicans, with his first vote for a Republican going to Mayra Flores in the 2022 Texas's 34th congressional district special election. In 2024, he started supporting international far-right political parties, activists, and causes, and has shared misinformation and numerous conspiracy theories. Since 2024, his views have been generally described as right-wing. Musk supported Barack Obama in 2008 and 2012, Hillary Clinton in 2016, Joe Biden in 2020, and Donald Trump in 2024. In the 2020 Democratic Party presidential primaries, Musk endorsed candidate Andrew Yang and expressed support for Yang's proposed universal basic income, and endorsed Kanye West's 2020 presidential campaign. In 2021, Musk publicly expressed opposition to the Build Back Better Act, a $3.5 trillion legislative package endorsed by Joe Biden that ultimately failed to pass due to unanimous opposition from congressional Republicans and several Democrats. In 2022, gave over $50 million to Citizens for Sanity, a conservative political action committee. In 2023, he supported Republican Ron DeSantis for the 2024 U.S. presidential election, giving $10 million to his campaign, and hosted DeSantis's campaign announcement on a Twitter Spaces event. From June 2023 to January 2024, Musk hosted a bipartisan set of X Spaces with Republican and Democratic candidates, including Robert F. Kennedy Jr., Vivek Ramaswamy, and Dean Phillips. In October 2025, former vice-president Kamala Harris commented that it was a mistake from the Democratic side to not invite Musk to a White House electric vehicle event organized in August 2021 and featuring executives from General Motors, Ford and Stellantis, despite Tesla being "the major American manufacturer of extraordinary innovation in this space." Fortune remarked that this was a nod to United Auto Workers and organized labor. Harris said presidents should put aside political loyalties when it came to recognizing innovation, and guessed that the non-invitation impacted Musk's perspective. Fortune noted that, at the time, Musk said, "Yeah, seems odd that Tesla wasn't invited." A month later, he criticized Biden as "not the friendliest administration." Jacob Silverman, author of the book Gilded Rage: Elon Musk and the Radicalization of Silicon Valley, said that the tech industry represented by Musk, Thiel, Andreessen and other capitalists, actually flourished under Biden, but the tech leaders chose Trump for their common ground on cultural issues. By early 2024, Musk had become a vocal and financial supporter of Donald Trump. In July 2024, minutes after the attempted assassination of Donald Trump, Musk endorsed him for president saying; "I fully endorse President Trump and hope for his rapid recovery." During the presidential campaign, Musk joined Trump on stage at a campaign rally, and during the campaign promoted conspiracy theories and falsehoods about Democrats, election fraud and immigration, in support of Trump. Musk was the largest individual donor of the 2024 election. In 2025, Musk contributed $19 million to the Wisconsin Supreme Court race, hoping to influence the state's future redistricting efforts and its regulations governing car manufacturers and dealers. In 2023, Musk said he shunned the World Economic Forum because it was boring. The organization commented that they had not invited him since 2015. He has participated in Dialog, dubbed "Tech Bilderberg" and organized by Peter Thiel and Auren Hoffman, though. Musk's international political actions and comments have come under increasing scrutiny and criticism, especially from the governments and leaders of France, Germany, Norway, Spain and the United Kingdom, particularly due to his position in the U.S. government as well as ownership of X. An NBC News analysis found he had boosted far-right political movements to cut immigration and curtail regulation of business in at least 18 countries on six continents since 2023. During his speech after the second inauguration of Donald Trump, Musk twice made a gesture interpreted by many as a Nazi or a fascist Roman salute.[e] He thumped his right hand over his heart, fingers spread wide, and then extended his right arm out, emphatically, at an upward angle, palm down and fingers together. He then repeated the gesture to the crowd behind him. As he finished the gestures, he said to the crowd, "My heart goes out to you. It is thanks to you that the future of civilization is assured." It was widely condemned as an intentional Nazi salute in Germany, where making such gestures is illegal. The Anti-Defamation League said it was not a Nazi salute, but other Jewish organizations disagreed and condemned the salute. American public opinion was divided on partisan lines as to whether it was a fascist salute. Musk dismissed the accusations of Nazi sympathies, deriding them as "dirty tricks" and a "tired" attack. Neo-Nazi and white supremacist groups celebrated it as a Nazi salute. Multiple European political parties demanded that Musk be banned from entering their countries. The concept of DOGE emerged in a discussion between Musk and Donald Trump, and in August 2024, Trump committed to giving Musk an advisory role, with Musk accepting the offer. In November and December 2024, Musk suggested that the organization could help to cut the U.S. federal budget, consolidate the number of federal agencies, and eliminate the Consumer Financial Protection Bureau, and that its final stage would be "deleting itself". In January 2025, the organization was created by executive order, and Musk was designated a "special government employee". Musk led the organization and was a senior advisor to the president, although his official role is not clear. In sworn statement during a lawsuit, the director of the White House Office of Administration stated that Musk "is not an employee of the U.S. DOGE Service or U.S. DOGE Service Temporary Organization", "is not the U.S. DOGE Service administrator", and has "no actual or formal authority to make government decisions himself". Trump said two days later that he had put Musk in charge of DOGE. A federal judge has ruled that Musk acted as the de facto leader of DOGE. Musk's role in the second Trump administration, particularly in response to DOGE, has attracted public backlash. He was criticized for his treatment of federal government employees, including his influence over the mass layoffs of the federal workforce. He has prioritized secrecy within the organization and has accused others of violating privacy laws. A Senate report alleged that Musk could avoid up to $2 billion in legal liability as a result of DOGE's actions. In May 2025, Bill Gates accused Musk of "killing the world's poorest children" through his cuts to USAID, which modeling by Boston University estimated had resulted in 300,000 deaths by this time, most of them of children. By November 2025, the estimated death toll had increased to 400,000 children and 200,000 adults. Musk announced on May 28, 2025, that he would depart from the Trump administration as planned when the special government employee's 130 day deadline expired, with a White House official confirming that Musk's offboarding from the Trump administration was already underway. His departure was officially confirmed during a joint Oval Office press conference with Trump on May 30, 2025. @realDonaldTrump is in the Epstein files. That is the real reason they have not been made public. June 5, 2025 After leaving office, Musk criticized the Trump administration's Big Beautiful Bill, calling it a "disgusting abomination" due to its provisions increasing the deficit. A feud began between Musk and Trump, with its most notable event being Musk alleging Trump had ties to sex offender Jeffrey Epstein on X (formerly Twitter) on June 5, 2025. Trump responded on Truth Social stating that Musk went "CRAZY" after the "EV Mandate" was purportedly taken away and threatened to cut Musk's government contracts. Musk then called for a third Trump impeachment. The next day, Trump stated that he did not wish to reconcile with Musk, and added that Musk would face "very serious consequences" if he funds Democratic candidates. On June 11, Musk publicly apologized for the tweets against Trump, saying they "went too far". Views November 6, 2022 Rejecting the conservative label, Musk has described himself as a political moderate, even as his views have become more right-wing over time. His views have been characterized as libertarian and far-right, and after his involvement in European politics, they have received criticism from world leaders such as Emmanuel Macron and Olaf Scholz. Within the context of American politics, Musk supported Democratic candidates up until 2022, at which point he voted for a Republican for the first time. He has stated support for universal basic income, gun rights, freedom of speech, a tax on carbon emissions, and H-1B visas. Musk has expressed concern about issues such as artificial intelligence (AI) and climate change, and has been a critic of wealth tax, short-selling, and government subsidies. An immigrant himself, Musk has been accused of being anti-immigration, and regularly blames immigration policies for illegal immigration. He is also a pronatalist who believes population decline is the biggest threat to civilization, and identifies as a cultural Christian. Musk has long been an advocate for space colonization, especially the colonization of Mars. He has repeatedly pushed for humanity colonizing Mars, in order to become an interplanetary species and lower the risks of human extinction. Musk has promoted conspiracy theories and made controversial statements that have led to accusations of racism, sexism, antisemitism, transphobia, disseminating disinformation, and support of white pride. While describing himself as a "pro-Semite", his comments regarding George Soros and Jewish communities have been condemned by the Anti-Defamation League and the Biden White House. Musk was criticized during the COVID-19 pandemic for making unfounded epidemiological claims, defying COVID-19 lockdowns restrictions, and supporting the Canada convoy protest against vaccine mandates. He has amplified false claims of white genocide in South Africa. Musk has been critical of Israel's actions in the Gaza Strip during the Gaza war, praised China's economic and climate goals, suggested that Taiwan and China should resolve cross-strait relations, and was described as having a close relationship with the Chinese government. In Europe, Musk expressed support for Ukraine in 2022 during the Russian invasion, recommended referendums and peace deals on the annexed Russia-occupied territories, and supported the far-right Alternative for Germany political party in 2024. Regarding British politics, Musk blamed the 2024 UK riots on mass migration and open borders, criticized Prime Minister Keir Starmer for what he described as a "two-tier" policing system, and was subsequently attacked as being responsible for spreading misinformation and amplifying the far-right. He has also voiced his support for far-right activist Tommy Robinson and pledged electoral support for Reform UK. In February 2026, Musk described Spanish Prime Minister Pedro Sánchez as a "tyrant" following Sánchez's proposal to prohibit minors under the age of 16 from accessing social media platforms. Legal affairs In 2018, Musk was sued by the U.S. Securities and Exchange Commission (SEC) for a tweet stating that funding had been secured for potentially taking Tesla private.[f] The securities fraud lawsuit characterized the tweet as false, misleading, and damaging to investors, and sought to bar Musk from serving as CEO of publicly traded companies. Two days later, Musk settled with the SEC, without admitting or denying the SEC's allegations. As a result, Musk and Tesla were fined $20 million each, and Musk was forced to step down for three years as Tesla chairman but was able to remain as CEO. Shareholders filed a lawsuit over the tweet, and in February 2023, a jury found Musk and Tesla not liable. Musk has stated in interviews that he does not regret posting the tweet that triggered the SEC investigation. In 2019, Musk stated in a tweet that Tesla would build half a million cars that year. The SEC reacted by asking a court to hold him in contempt for violating the terms of the 2018 settlement agreement. A joint agreement between Musk and the SEC eventually clarified the previous agreement details, including a list of topics about which Musk needed preclearance. In 2020, a judge blocked a lawsuit that claimed a tweet by Musk regarding Tesla stock price ("too high imo") violated the agreement. Freedom of Information Act (FOIA)-released records showed that the SEC concluded Musk had subsequently violated the agreement twice by tweeting regarding "Tesla's solar roof production volumes and its stock price". In October 2023, the SEC sued Musk over his refusal to testify a third time in an investigation into whether he violated federal law by purchasing Twitter stock in 2022. In February 2024, Judge Laurel Beeler ruled that Musk must testify again. In January 2025, the SEC filed a lawsuit against Musk for securities violations related to his purchase of Twitter. In January 2024, Delaware judge Kathaleen McCormick ruled in a 2018 lawsuit that Musk's $55 billion pay package from Tesla be rescinded. McCormick called the compensation granted by the company's board "an unfathomable sum" that was unfair to shareholders. The Delaware Supreme Court overturned McCormick's decision in December 2025, restoring Musk's compensation package and awarding $1 in nominal damages. Personal life Musk became a U.S. citizen in 2002. From the early 2000s until late 2020, Musk resided in California, where both Tesla and SpaceX were founded. He then relocated to Cameron County, Texas, saying that California had become "complacent" about its economic success. While hosting Saturday Night Live in 2021, Musk stated that he has Asperger syndrome (an outdated term for autism spectrum disorder). When asked about his experience growing up with Asperger's syndrome in a TED2022 conference in Vancouver, Musk stated that "the social cues were not intuitive ... I would just tend to take things very literally ... but then that turned out to be wrong — [people were not] simply saying exactly what they mean, there's all sorts of other things that are meant, and [it] took me a while to figure that out." Musk suffers from back pain and has undergone several spine-related surgeries, including a disc replacement. In 2000, he contracted a severe case of malaria while on vacation in South Africa. Musk has stated he uses doctor-prescribed ketamine for occasional depression and that he doses "a small amount once every other week or something like that"; since January 2024, some media outlets have reported that he takes ketamine, marijuana, LSD, ecstasy, mushrooms, cocaine and other drugs. Musk at first refused to comment on his alleged drug use, before responding that he had not tested positive for drugs, and that if drugs somehow improved his productivity, "I would definitely take them!". The New York Times' investigations revealed Musk's overuse of ketamine and numerous other drugs, as well as strained family relationships and concerns from close associates who have become troubled by his public behavior as he became more involved in political activities and government work. According to The Washington Post, President Trump described Musk as "a big-time drug addict". Through his own label Emo G Records, Musk released a rap track, "RIP Harambe", on SoundCloud in March 2019. The following year, he released an EDM track, "Don't Doubt Ur Vibe", featuring his own lyrics and vocals. Musk plays video games, which he stated has a "'restoring effect' that helps his 'mental calibration'". Some games he plays include Quake, Diablo IV, Elden Ring, and Polytopia. Musk once claimed to be one of the world's top video game players but has since admitted to "account boosting", or cheating by hiring outside services to achieve top player rankings. Musk has justified the boosting by claiming that all top accounts do it so he has to as well to remain competitive. In 2024 and 2025, Musk criticized the video game Assassin's Creed Shadows and its creator Ubisoft for "woke" content. Musk posted to X that "DEI kills art" and specified the inclusion of the historical figure Yasuke in the Assassin's Creed game as offensive; he also called the game "terrible". Ubisoft responded by saying that Musk's comments were "just feeding hatred" and that they were focused on producing a game not pushing politics. Musk has fathered at least 14 children, one of whom died as an infant. The Wall Street Journal reported in 2025 that sources close to Musk suggest that the "true number of Musk's children is much higher than publicly known". He had six children with his first wife, Canadian author Justine Wilson, whom he met while attending Queen's University in Ontario, Canada; they married in 2000. In 2002, their first child Nevada Musk died of sudden infant death syndrome at the age of 10 weeks. After his death, the couple used in vitro fertilization (IVF) to continue their family; they had twins in 2004, followed by triplets in 2006. The couple divorced in 2008 and have shared custody of their children. The elder twin he had with Wilson came out as a trans woman and, in 2022, officially changed her name to Vivian Jenna Wilson, adopting her mother's surname because she no longer wished to be associated with Musk. Musk began dating English actress Talulah Riley in 2008. They married two years later at Dornoch Cathedral in Scotland. In 2012, the couple divorced, then remarried the following year. After briefly filing for divorce in 2014, Musk finalized a second divorce from Riley in 2016. Musk then dated the American actress Amber Heard for several months in 2017; he had reportedly been "pursuing" her since 2012. In 2018, Musk and Canadian musician Grimes confirmed they were dating. Grimes and Musk have three children, born in 2020, 2021, and 2022.[g] Musk and Grimes originally gave their eldest child the name "X Æ A-12", which would have violated California regulations as it contained characters that are not in the modern English alphabet; the names registered on the birth certificate are "X" as a first name, "Æ A-Xii" as a middle name, and "Musk" as a last name. They received criticism for choosing a name perceived to be impractical and difficult to pronounce; Musk has said the intended pronunciation is "X Ash A Twelve". Their second child was born via surrogacy. Despite the pregnancy, Musk confirmed reports that the couple were "semi-separated" in September 2021; in an interview with Time in December 2021, he said he was single. In October 2023, Grimes sued Musk over parental rights and custody of X Æ A-Xii. Elon Musk has taken X Æ A-Xii to multiple official events in Washington, D.C. during Trump's second term in office. Also in July 2022, The Wall Street Journal reported that Musk allegedly had an affair with Nicole Shanahan, the wife of Google co-founder Sergey Brin, in 2021, leading to their divorce the following year. Musk denied the report. Musk also had a relationship with Australian actress Natasha Bassett, who has been described as "an occasional girlfriend". In October 2024, The New York Times reported Musk bought a Texas compound for his children and their mothers, though Musk denied having done so. Musk also has four children with Shivon Zilis, director of operations and special projects at Neuralink: twins born via IVF in 2021, a child born in 2024 via surrogacy and a child born in 2025.[h] On February 14, 2025, Ashley St. Clair, an influencer and author, posted on X claiming to have given birth to Musk's son Romulus five months earlier, which media outlets reported as Musk's supposed thirteenth child.[i] On February 22, 2025, it was reported that St Clair had filed for sole custody of her five-month-old son and for Musk to be recognised as the child's father. On March 31, 2025, Musk wrote that, while he was unsure if he was the father of St. Clair's child, he had paid St. Clair $2.5 million and would continue paying her $500,000 per year.[j] Later reporting from the Wall Street Journal indicated that $1 million of these payments to St. Clair were structured as a loan. In 2014, Musk and Ghislaine Maxwell appeared together in a photograph taken at an Academy Awards after-party, which Musk later described as a "photobomb". The January 2026 Epstein files contain emails between Musk and Epstein from 2012 to 2013, after Epstein's first conviction. Emails released on January 30, 2026, indicated that Epstein invited Musk to visit his private island on multiple occasions. The correspondence showed that while Epstein repeatedly encouraged Musk to attend, Musk did not visit the island. In one instance, Musk discussed the possibility of attending a party with his then-wife Talulah Riley and asked which day would be the "wildest party"; according to the emails, the visit did not take place after Epstein later cancelled the plans.[k] On Christmas day in 2012, Musk emailed Epstein asking "Do you have any parties planned? I’ve been working to the edge of sanity this year and so, once my kids head home after Christmas, I really want to hit the party scene in St Barts or elsewhere and let loose. The invitation is much appreciated, but a peaceful island experience is the opposite of what I’m looking for". Epstein replied that the "ratio on my island" might make Musk's wife uncomfortable to which Musk responded, "Ratio is not a problem for Talulah". On September 11, 2013, Epstein sent an email asking Musk if he had any plans for coming to New York for the opening of the United Nations General Assembly where many "interesting people" would be coming to his house to which Musk responded that "Flying to NY to see UN diplomats do nothing would be an unwise use of time". Epstein responded by stating "Do you think i am retarded. Just kidding, there is no one over 25 and all very cute." Musk has denied any close relationship with Epstein and described him as a "creep" who attempted to ingratiate himself with influential people. When Musk was asked in 2019 if he introduced Epstein to Mark Zuckerberg, Musk responded: "I don’t recall introducing Epstein to anyone, as I don’t know the guy well enough to do so." The released emails nonetheless showed cordial exchanges on a range of topics, including Musk's inquiry about parties on the island. The correspondence also indicated that Musk suggested hosting Epstein at SpaceX, while Epstein separately discussed plans to tour SpaceX and bring "the girls", though there is no evidence that such a visit occurred. Musk has described the release of the files a "distraction", later accusing the second Trump administration of suppressing them to protect powerful individuals, including Trump himself.[l] Wealth Elon Musk is the wealthiest person in the world, with an estimated net worth of US$690 billion as of January 2026, according to the Bloomberg Billionaires Index, and $852 billion according to Forbes, primarily from his ownership stakes in SpaceX and Tesla. Having been first listed on the Forbes Billionaires List in 2012, around 75% of Musk's wealth was derived from Tesla stock in November 2020, although he describes himself as "cash poor". According to Forbes, he became the first person in the world to achieve a net worth of $300 billion in 2021; $400 billion in December 2024; $500 billion in October 2025; $600 billion in mid-December 2025; $700 billion later that month; and $800 billion in February 2026. In November 2025, a Tesla pay package worth potentially $1 trillion for Musk was approved, which he is to receive over 10 years if he meets specific goals. Public image Although his ventures have been highly influential within their separate industries starting in the 2000s, Musk only became a public figure in the early 2010s. He has been described as an eccentric who makes spontaneous and impactful decisions, while also often making controversial statements, contrary to other billionaires who prefer reclusiveness to protect their businesses. Musk's actions and his expressed views have made him a polarizing figure. Biographer Ashlee Vance described people's opinions of Musk as polarized due to his "part philosopher, part troll" persona on Twitter. He has drawn denouncement for using his platform to mock the self-selection of personal pronouns, while also receiving praise for bringing international attention to matters like British survivors of grooming gangs. Musk has been described as an American oligarch due to his extensive influence over public discourse, social media, industry, politics, and government policy. After Trump's re-election, Musk's influence and actions during the transition period and the second presidency of Donald Trump led some to call him "President Musk", the "actual president-elect", "shadow president" or "co-president". Awards for his contributions to the development of the Falcon rockets include the American Institute of Aeronautics and Astronautics George Low Transportation Award in 2008, the Fédération Aéronautique Internationale Gold Space Medal in 2010, and the Royal Aeronautical Society Gold Medal in 2012. In 2015, he received an honorary doctorate in engineering and technology from Yale University and an Institute of Electrical and Electronics Engineers Honorary Membership. Musk was elected a Fellow of the Royal Society (FRS) in 2018.[m] In 2022, Musk was elected to the National Academy of Engineering. Time has listed Musk as one of the most influential people in the world in 2010, 2013, 2018, and 2021. Musk was selected as Time's "Person of the Year" for 2021. Then Time editor-in-chief Edward Felsenthal wrote that, "Person of the Year is a marker of influence, and few individuals have had more influence than Musk on life on Earth, and potentially life off Earth too." Notes References Works cited Further reading External links |
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[SOURCE: https://en.wikipedia.org/wiki/Electromagnetic_radiation] | [TOKENS: 9829] |
Contents Electromagnetic radiation In physics, electromagnetic radiation (EMR) or electromagnetic wave (EMW) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency (inversely proportional to wavelength), ranging from radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, to gamma rays. All forms of EMR travel at the speed of light in a vacuum and exhibit wave–particle duality, behaving both as waves and as discrete particles called photons. Electromagnetic radiation is produced by accelerating charged particles such as from the Sun and other celestial bodies or artificially generated for various applications. Its interaction with matter depends on wavelength, influencing its uses in communication, medicine, industry, and scientific research. Radio waves enable broadcasting and wireless communication, infrared is used in thermal imaging, visible light is essential for vision, and higher-energy radiation, such as X-rays and gamma rays, is applied in medical imaging, cancer treatment, and industrial inspection. Exposure to high-energy radiation can pose health risks, making shielding and regulation necessary in certain applications. In quantum mechanics, an alternate way of viewing EMR is that it consists of photons, uncharged elementary particles with zero rest mass which are the quanta of the electromagnetic field, responsible for all electromagnetic interactions. Quantum electrodynamics is the theory of how EMR interacts with matter on an atomic level. Quantum effects provide additional sources of EMR, such as the transition of electrons to lower energy levels in an atom and black-body radiation. Physics Electromagnetic radiation is produced by accelerating charged particles and can be naturally emitted, as from the Sun and other celestial bodies, or artificially generated for various applications. The energy in electromagnetic waves is sometimes called radiant energy. The electromagnetic waves' energy does not need a propagating medium to travel through space; they move through a vacuum at the speed of light. Electric and magnetic fields obey the properties of superposition. Thus, a field due to any particular particle or time-varying electric or magnetic field contributes to the fields present in the same space due to other causes. Further, as they are vector fields, all magnetic and electric field vectors add together according to vector addition. For example, in optics two or more coherent light waves may interact and by constructive or destructive interference yield a resultant irradiance deviating from the sum of the component irradiances of the individual light waves. The electromagnetic fields of light are not affected by traveling through static electric or magnetic fields in a linear medium such as a vacuum. However, in nonlinear media, such as some crystals, interactions can occur between light and static electric and magnetic fields—these interactions include the Faraday effect and the Kerr effect. In refraction, a wave crossing from one medium to another of different density alters its speed and direction upon entering the new medium. The ratio of the refractive indices of the media determines the degree of refraction, and is summarized by Snell's law. Light of composite wavelengths (natural sunlight) disperses into a visible spectrum passing through a prism, because of the wavelength-dependent refractive index of the prism material (dispersion); that is, each component wave within the composite light is bent a different amount. EM radiation exhibits both wave properties and particle properties at the same time (known as wave–particle duality). Both wave and particle characteristics have been confirmed in many experiments. Wave characteristics are more apparent when EM radiation is measured over relatively large timescales and over large distances while particle characteristics are more evident when measuring small timescales and distances. For example, when electromagnetic radiation is absorbed by matter, particle-like properties will be more obvious when the average number of photons in the cube of the relevant wavelength is much smaller than 1. It is not so difficult to experimentally observe non-uniform deposition of energy when light is absorbed, however this alone is not evidence of "particulate" behavior. Rather, it reflects the quantum nature of matter. A quantum theory of the interaction between electromagnetic radiation and matter such as electrons is described by the theory of quantum electrodynamics. Electromagnetic waves can be polarized, reflected, refracted, or diffracted, and can interfere with each other. Some experiments display both the wave and particle natures of electromagnetic waves, such as the self-interference of a single photon. When a low intensity light is sent through an interferometer it will be detected by a photomultiplier or other sensitive detector only along one arm of the device, consistent with particle properties, and yet the accumulated effect of many such detections will be interference consistent with wave properties. In homogeneous, isotropic media, electromagnetic radiation is a transverse wave, meaning that its oscillations are perpendicular to the direction of energy transfer and travel. It comes from the following equations: ∇ ⋅ E = 0 ∇ ⋅ B = 0 {\displaystyle {\begin{aligned}\nabla \cdot \mathbf {E} &=0\\\nabla \cdot \mathbf {B} &=0\end{aligned}}} These equations predicate that any electromagnetic wave must be a transverse wave, where the electric field E and the magnetic field B are both perpendicular to the direction of wave propagation. The electric and magnetic parts of the field in an electromagnetic wave stand in a fixed ratio of strengths to satisfy the two Maxwell's equations that specify how one is produced from the other. In dissipation-less (lossless) media, these E and B fields are also in phase, with both reaching maxima and minima at the same points in space. In the far-field EM radiation which is described by the two source-free Maxwell curl operator equations, a time-change in one type of field is proportional to the curl of the other. These derivatives require that the E and B fields in EMR are in phase. An important aspect of light's nature is its frequency. The frequency of a wave is its rate of oscillation and is measured in hertz, the SI unit of frequency, where one hertz is equal to one oscillation per second. Light usually has multiple frequencies that sum to form the resultant wave. Different frequencies undergo different angles of refraction, a phenomenon known as dispersion. A monochromatic wave (a wave of a single frequency) consists of successive troughs and crests, and the distance between two adjacent crests or troughs is called the wavelength. Waves of the electromagnetic spectrum vary in size, from very long radio waves longer than a continent to very short gamma rays smaller than atom nuclei. Frequency is inversely proportional to wavelength, according to the equation: where v is the speed of the wave (c in a vacuum or less in other media), f is the frequency, and λ is the wavelength. As waves cross boundaries between different media, their speeds change but their frequencies remain constant. Electromagnetic waves in free space must be solutions of Maxwell's electromagnetic wave equation. Two main classes of solutions are known, namely plane waves and spherical waves. The plane waves may be viewed as the limiting case of spherical waves at a very large (ideally infinite) distance from the source. Both types of waves can have a waveform which is an arbitrary time function (so long as it is sufficiently differentiable to conform to the wave equation). As with any time function, this can be decomposed by means of Fourier analysis into its frequency spectrum, or individual sinusoidal components, each of which contains a single frequency, amplitude, and phase. Such a component wave is said to be monochromatic. Interference is the superposition of two or more waves resulting in a new wave pattern. If the fields have components in the same direction, they constructively interfere, while opposite directions cause destructive interference. Additionally, multiple polarization signals can be combined (i.e. interfered) to form new states of polarization, which is known as parallel polarization state generation. James Clerk Maxwell derived a wave form of the electric and magnetic equations, thus uncovering the wave-like nature of electric and magnetic fields and their symmetry. Because the speed of EM waves predicted by the wave equation coincided with the measured speed of light, Maxwell concluded that light itself is an EM wave. Maxwell's equations were confirmed by Heinrich Hertz through experiments with radio waves. Out of the four equations, two of the equations that Maxwell refined were Faraday's Law of Induction and Ampère's circuital law, which he extended by adding the displacement current term to the equations himself. Maxwell thought that the displacement current, which he viewed as the motion of bound charges, gave rise to the magnetic field. The other two equations are Gauss's law and Gauss's law for magnetism. Maxwell's equations established that some charges and currents (sources) produce local electromagnetic fields near them that do not radiate. Currents directly produce magnetic fields, but such fields of a magnetic-dipole–type that dies out with distance from the current. In a similar manner, moving charges pushed apart in a conductor by a changing electrical potential (such as in an antenna) produce an electric-dipole–type electrical field, but this also declines with distance. These fields make up the near field. Neither of these behaviours is responsible for EM radiation. Instead, they only efficiently transfer energy to a receiver very close to the source, such as inside a transformer. The near field has strong effects on its source, with any energy withdrawn by a receiver causing increased load (decreased electrical reactance) on the source. The near field does not propagate freely into space, carrying energy away without a distance limit, but rather oscillates, returning its energy to the transmitter if it is not absorbed by a receiver. By contrast, the far field is composed of radiation that is free of the transmitter, in the sense that the transmitter requires the same power to send changes in the field out regardless of whether anything absorbs the signal, e.g. a radio station does not need to increase its power when more receivers use the signal. This far part of the electromagnetic field is electromagnetic radiation. The far fields propagate (radiate) without allowing the transmitter to affect them. This causes them to be independent in the sense that their existence and their energy, after they have left the transmitter, is completely independent of both transmitter and receiver. Due to conservation of energy, the amount of power passing through any closed surface drawn around the source is the same. The power density of EM radiation from an isotropic source decreases with the inverse square of the distance from the source; this is called the inverse-square law. Field intensity due to dipole parts of the near field varies according to an inverse-cube law, and thus fades with distance. In the Liénard–Wiechert potential formulation of the electric and magnetic fields due to motion of a single particle (according to Maxwell's equations), the terms associated with acceleration of the particle are those that are responsible for the part of the field that is regarded as electromagnetic radiation. By contrast, the term associated with the changing static electric field of the particle and the magnetic term that results from the particle's uniform velocity are both associated with the near field, and do not comprise electromagnetic radiation. An anomaly arose in the late 19th century involving a contradiction between the wave theory of light and measurements of the electromagnetic spectra that were being emitted by thermal radiators known as black bodies. Physicists struggled with this problem unsuccessfully for many years, and it later became known as the ultraviolet catastrophe. In 1900, Max Planck developed a new theory of black-body radiation that explained the observed spectrum. Planck's theory was based on the idea that black bodies emit light (and other electromagnetic radiation) only as discrete bundles or packets of energy. These packets were called quanta. In 1905, Albert Einstein proposed that light quanta be regarded as real particles. Later the particle of light was given the name photon, to correspond with other particles being described around this time, such as the electron and proton. A photon has an energy, E, proportional to its frequency, f, by where h is the Planck constant, λ {\displaystyle \lambda } is the wavelength and c is the speed of light. This is sometimes known as the Planck–Einstein equation. In quantum theory (see first quantization) the energy of the photons is thus directly proportional to the frequency of the EMR wave. Likewise, the momentum p of a photon is also proportional to its frequency and inversely proportional to its wavelength: The source of Einstein's proposal that light was composed of particles (or could act as particles in some circumstances) was an experimental anomaly not explained by the wave theory: the photoelectric effect, in which light striking a metal surface ejected electrons from the surface, causing an electric current to flow across an applied voltage. Experimental measurements demonstrated that the energy of individual ejected electrons was proportional to the frequency, rather than the intensity, of the light. Furthermore, below a certain minimum frequency, which depended on the particular metal, no current would flow regardless of the intensity. These observations appeared to contradict the wave theory, and for years physicists tried to find an explanation. In 1905, Einstein explained this phenomenon by resurrecting the particle theory of light. Because of the preponderance of evidence in favor of the wave theory, however, Einstein's ideas were met initially with great skepticism among established physicists. Eventually Einstein's explanation was accepted as new particle-like behavior of light was observed, such as the Compton effect. As a photon is absorbed by an atom, it excites the atom, elevating an electron to a higher energy level (one that is on average farther from the nucleus). When an electron in an excited molecule or atom descends to a lower energy level, it emits a photon of light at a frequency corresponding to the energy difference. Since the energy levels of electrons in atoms are discrete, each element and each molecule emits and absorbs its own characteristic frequencies. Immediate photon emission is called fluorescence, a type of photoluminescence. An example is visible light emitted from fluorescent paints, in response to ultraviolet (blacklight). Many other fluorescent emissions are known in spectral bands other than visible light. Delayed emission is called phosphorescence. Quantum mechanics also governs emission, which is seen when an emitting gas glows due to excitation of the atoms from any mechanism, including heat. As electrons descend to lower energy levels, a spectrum is emitted that represents the jumps between the energy levels of the electrons, but lines are seen because again emission happens only at particular energies after excitation. An example is the emission spectrum of nebulae. Rapidly moving electrons are most sharply accelerated when they encounter a region of force, so they are responsible for producing much of the highest frequency electromagnetic radiation observed in nature. These phenomena can be used to detect the composition of gases lit from behind (absorption spectra) and for glowing gases (emission spectra). Spectroscopy (for example) determines what chemical elements comprise a particular star. Shifts in the frequency of the spectral lines for an element, called a redshift, can be used to determine the star's cosmological distance.: 181 The modern theory that explains the nature of light includes the notion of wave–particle duality. The theory is based on the concept that every quantum entity can show wave-like or particle-like behaviors, depending on observation. The observation led to the collapse of the entity's wave function. If it is based on the Copenhagen interpretation, the observation does really collapse the wave function; for the many-worlds interpretation, all possible outcomes of the collapse happened in parallel universes; for the pilot wave theory, the particle behaviour is simply determined by waves. The duality nature of a real photon has been observed in the double-slit experiment. Together, wave and particle effects fully explain the emission and absorption spectra of EM radiation. The matter-composition of the medium through which the light travels determines the nature of the absorption and emission spectrum. These bands correspond to the allowed energy levels in the atoms. Dark bands in the absorption spectrum are due to the atoms in an intervening medium between source and observer. The atoms absorb certain frequencies of the light between emitter and detector/eye, then emit them in all directions. A dark band appears to the detector, due to the radiation scattered out of the light beam. For instance, dark bands in the light emitted by a distant star are due to the atoms in the star's atmosphere. In empty space (vacuum), electromagnetic radiation travels at the speed of light, c {\displaystyle c} , 299,792,458 meters per second (approximately 186,000 miles per second). In a medium other than vacuum it travels at a lower velocity v {\displaystyle v} , given by a dimensionless parameter between 0 and 1 characteristic of the medium called the velocity factor V F {\displaystyle {\mathit {VF}}} or its reciprocal, the refractive index n {\displaystyle n} : The reason for this is that in matter the electric and magnetic fields of the wave are slowed because they polarize the charged particles in the medium they pass through.: 401 The oscillating electric field causes nearby positive and negative charges in atoms to move slightly apart and together, inducing an oscillating polarization, creating an electric polarization field. The oscillating magnetic field moves nearby magnetic dipoles, inducing an oscillating magnetization, creating an induced oscillating magnetic field. These induced fields, superposed on the original wave fields, slow the wave (Ewald–Oseen extinction theorem). The amount of slowing depends on the electromagnetic properties of the medium, the electric permittivity and magnetic permeability. In the SI system of units, empty space has a vacuum permittivity of ϵ 0 = {\displaystyle \epsilon _{\text{0}}=} 8.854×10−12 F/m (farads per meter) and a vacuum permeability of μ 0 = {\displaystyle \mu _{\text{0}}=} 1.257×10−6 H/m (henries per meter). These universal constants determine the speed of light in a vacuum: In a medium that is isotropic and linear, which means the electric polarization is proportional to the electric field D = ϵ E {\displaystyle \mathbf {D} =\epsilon \mathbf {E} } and the magnetization is proportional to the magnetic field H = 1 μ B {\displaystyle \mathbf {H} ={1 \over \mu }\mathbf {B} } . The speed of the waves, the V F {\displaystyle {\mathit {VF}}} , and the refractive index are determined by only two parameters: the electric permittivity ϵ {\displaystyle \epsilon } of the medium in farads per meter, and the magnetic permeability of the medium μ {\displaystyle \mu } in henrys per meter: 401 If the permittivity and permeability of the medium is constant for different frequency EM waves, this is called a non-dispersive medium.: 417–418 In this case all EM wave frequencies would travel at the same velocity, and the waveshape stays constant as it travels. However in real matter ϵ {\displaystyle \epsilon } and μ {\displaystyle \mu } typically vary with frequency, this is called a dispersive medium. In dispersive media different spectral bands have different propagation characteristics, and an arbitrary wave changes shape as it travels through the medium. History of discovery Electromagnetic radiation of wavelengths other than those of visible light were discovered in the early 19th century. The discovery of infrared radiation is ascribed to astronomer William Herschel, who published his results in 1800 before the Royal Society of London. Herschel used a glass prism to refract light from the Sun and detected invisible rays that caused heating beyond the red part of the spectrum, through an increase in the temperature recorded with a thermometer. These "calorific rays" were later termed infrared. In 1801 German physicist Johann Wilhelm Ritter discovered ultraviolet in an experiment similar to Herschel's, using sunlight and a glass prism. Ritter noted that invisible rays near the violet edge of a solar spectrum dispersed by a triangular prism darkened silver chloride preparations more quickly than did the nearby violet light. Ritter's experiments were an early precursor to what would become photography. Ritter noted that the ultraviolet rays (which at first were called "chemical rays") were capable of causing chemical reactions. In 1862–64 James Clerk Maxwell developed equations for the electromagnetic field which suggested that waves in the field would travel with a speed that was very close to the known speed of light. Maxwell therefore suggested that visible light (as well as invisible infrared and ultraviolet rays by inference) all consisted of propagating disturbances (or radiation) in the electromagnetic field. Radio waves were first produced deliberately by Heinrich Hertz in 1887, using electrical circuits calculated to produce oscillations at a much lower frequency than that of visible light, following recipes for producing oscillating charges and currents suggested by Maxwell's equations. Hertz also developed ways to detect these waves, and produced and characterized what were later termed radio waves and microwaves.: 286, 7 Wilhelm Röntgen discovered and named X-rays. After experimenting with high voltages applied to an evacuated tube on 8 November 1895, he noticed a fluorescence on a nearby plate of coated glass. In one month, he discovered X-rays' main properties.: 307 The last portion of the EM spectrum to be discovered was associated with radioactivity. Henri Becquerel found that uranium salts caused fogging of an unexposed photographic plate through a covering paper in a manner similar to X-rays, and Marie Curie discovered that only certain elements gave off these rays of energy, soon discovering the intense radiation of radium. The radiation from pitchblende was differentiated into alpha rays (alpha particles) and beta rays (beta particles) by Ernest Rutherford through simple experimentation in 1899, but these proved to be charged particulate types of radiation. However, in 1900 the French scientist Paul Villard discovered a third neutrally charged and especially penetrating type of radiation from radium, and after he described it, Rutherford realized it must be yet a third type of radiation, which in 1903 Rutherford named gamma rays. In 1910 British physicist William Henry Bragg demonstrated that gamma rays are electromagnetic radiation, not particles, and in 1914 Rutherford and Edward Andrade measured their wavelengths, finding that they were similar to X-rays but with shorter wavelengths and higher frequency, although a 'cross-over' between X and gamma rays makes it possible to have X-rays with a higher energy (and hence shorter wavelength) than gamma rays and vice versa. The origin of the ray differentiates them, gamma rays tend to be natural phenomena originating from the unstable nucleus of an atom and X-rays are electrically generated (and hence man-made) unless they are as a result of bremsstrahlung X-radiation caused by the interaction of fast moving particles (such as beta particles) colliding with certain materials, usually of higher atomic numbers.: 308, 9 Electromagnetic spectrum EM radiation (the designation 'radiation' excludes static electric and magnetic and near fields) is classified by wavelength into radio, microwave, infrared, visible, ultraviolet, X-rays, and gamma rays. Arbitrary electromagnetic waves can be expressed by Fourier analysis in terms of sinusoidal waves (monochromatic radiation), which in turn can each be classified into these regions of the EMR spectrum. For certain classes of EM waves, the waveform is most usefully treated as random, and then spectral analysis must be done by slightly different mathematical techniques appropriate to random or stochastic processes. In such cases, the individual frequency components are represented in terms of their power content, and the phase information is not preserved. Such a representation is called the power spectral density of the random process. Random electromagnetic radiation requiring this kind of analysis is, for example, encountered in the interior of stars, and in certain other very wideband forms of radiation such as the zero-point wave field of the electromagnetic vacuum. The behavior of EM radiation and its interaction with matter depends on its frequency, and changes qualitatively as the frequency changes. Lower frequencies have longer wavelengths, and higher frequencies have shorter wavelengths, and are associated with photons of higher energy. There is no fundamental limit known to these wavelengths or energies, at either end of the spectrum, although photons with energies near the Planck energy or exceeding it (far too high to have ever been observed) will require new physical theories to describe. Electromagnetic radiation phenomena with wavelengths ranging from one meter to one millimeter are called microwaves; with frequencies between 300 MHz (0.3 GHz) and 300 GHz. When radio waves impinge upon a conductor, they couple to the conductor, travel along it, and induce an electric current on the conductor surface by moving the electrons of the conducting material in correlated bunches of charge. At radio and microwave frequencies, EMR interacts with matter largely as a bulk collection of charges which are spread out over large numbers of affected atoms. In electrical conductors, such induced bulk movement of charges (electric currents) results in absorption of the EMR, or else separations of charges that cause generation of new EMR (effective reflection of the EMR). An example is absorption or emission of radio waves by antennas, or absorption of microwaves by water or other molecules with an electric dipole moment, as for example inside a microwave oven. These interactions produce either electric currents or heat, or both. Like radio and microwave, infrared (IR) is reflected by metals (and also most EMR, well into the ultraviolet range). However, unlike lower-frequency radio and microwave radiation, infrared EMR commonly interacts with dipoles present in single molecules, which change as atoms vibrate at the ends of a single chemical bond. It is consequently absorbed by a wide range of substances, causing them to increase in temperature as the vibrations dissipate as heat. The same process, run in reverse, causes bulk substances to radiate in the infrared spontaneously (see thermal radiation section below). Infrared radiation is divided into spectral subregions. While different subdivision schemes exist, the spectrum is commonly divided as near-infrared (0.75–1.4 μm), short-wavelength infrared (1.4–3 μm), mid-wavelength infrared (3–8 μm), long-wavelength infrared (8–15 μm) and far infrared (15–1000 μm). Some animals, such as snakes, have thermo-sensitive membranes (pit organs) that can detect temperature differences, allowing them to sense infrared radiation. Natural sources produce EM radiation across the spectrum. EM radiation with a wavelength between approximately 400 nm and 700 nm is directly detected by the human eye and perceived as visible light. Other wavelengths, especially nearby infrared (longer than 700 nm) and ultraviolet (shorter than 400 nm) are also sometimes referred to as light. As frequency increases into the visible range, photons have enough energy to change the bond structure of some individual molecules. It is not a coincidence that this happens in the visible range, as the mechanism of vision involves the change in bonding of a single molecule, retinal, which absorbs a single photon. The change in retinal causes a change in the shape of the rhodopsin protein it is contained in, which starts the biochemical process that causes the retina of the human eye to sense the light. Visible light is able to affect only a tiny percentage of all molecules. Usually not in a permanent or damaging way, rather the photon excites an electron which then emits another photon when returning to its original position. This is the source of color produced by most dyes. Retinal is an exception. When a photon is absorbed, the retinal permanently changes structure from cis to trans, and requires a protein to convert it back, i.e. reset it to be able to function as a light detector again. Photosynthesis becomes possible in this range as well, for the same reason. A single molecule of chlorophyll is excited by a single photon. In plant tissues that conduct photosynthesis, carotenoids act to quench electronically excited chlorophyll produced by visible light in a process called non-photochemical quenching, to prevent reactions that would otherwise interfere with photosynthesis at high light levels. Limited evidence indicate that some reactive oxygen species are created by visible light in skin, and that these may have some role in photoaging, in the same manner as ultraviolet A. Infrared, microwaves, and radio waves are known to damage molecules and biological tissue only by bulk heating, not excitation from single photons of the radiation. As frequency increases into the ultraviolet, photons now carry enough energy (about three electron volts or more) to excite certain doubly bonded molecules into permanent chemical rearrangement. In DNA, this causes lasting damage. DNA is also indirectly damaged by reactive oxygen species produced by ultraviolet A (UVA), which has energy too low to damage DNA directly. This is why ultraviolet at all wavelengths can damage DNA, and is capable of causing cancer, and (for UVB) skin burns (sunburn) that are far worse than would be produced by simple heating (temperature increase) effects. At the higher end of the ultraviolet range, the energy of photons becomes large enough to impart enough energy to electrons to cause them to be liberated from the atom, in a process called photoionisation. The energy required for this is always larger than about 10 electron volt (eV) corresponding with wavelengths smaller than 124 nm (some sources suggest a more realistic cutoff of 33 eV, which is the energy required to ionize water). This high end of the ultraviolet spectrum with energies in the approximate ionization range, is sometimes called "extreme UV". Ionizing UV is strongly filtered by the Earth's atmosphere. Electromagnetic radiation composed of photons that carry minimum-ionization energy, or more (which includes the entire spectrum with shorter wavelengths), is therefore termed ionizing radiation. (Many other kinds of ionizing radiation are made of non-EM particles.) Electromagnetic-type ionizing radiation extends from the extreme ultraviolet to all higher frequencies and shorter wavelengths, which means that all X-rays and gamma rays qualify. These are capable of the most severe types of molecular damage, which can happen in biology to any type of biomolecule, including mutation and cancer, and often at great depths below the skin, since the higher end of the X-ray spectrum, and all of the gamma ray spectrum, penetrate matter. Atmosphere and magnetosphere Most UV and X-rays are blocked by absorption first from molecular nitrogen, and then (for wavelengths in the upper UV) from the electronic excitation of dioxygen and finally ozone at the mid-range of UV. Only 30% of the Sun's ultraviolet light reaches the ground, and almost all of this is well transmitted. Visible light is well transmitted in air, a property known as an atmospheric window, as it is not energetic enough to excite nitrogen, oxygen, or ozone, but too energetic to excite molecular vibrational frequencies of water vapor and carbon dioxide. Absorption bands in the infrared are due to modes of vibrational excitation in water vapor. However, at energies too low to excite water vapor, the atmosphere becomes transparent again, allowing free transmission of most microwave and radio waves. Finally, at radio wavelengths longer than 10 m or so (about 30 MHz), the air in the lower atmosphere remains transparent to radio, but plasma in certain layers of the ionosphere begins to interact with radio waves (see skywave). This property allows some longer wavelengths (100 m or 3 MHz) to be reflected and results in shortwave radio beyond line-of-sight. However, certain ionospheric effects begin to block incoming radiowaves from space, when their frequency is less than about 10 MHz (wavelength longer than about 30 m). Thermal and electromagnetic radiation as a form of heat The basic structure of matter involves charged particles bound together. When electromagnetic radiation impinges on matter, it causes the charged particles to oscillate and gain energy. The ultimate fate of this energy depends on the context. It could be immediately re-radiated and appear as scattered, reflected, or transmitted radiation. It may get dissipated into other microscopic motions within the matter, coming to thermal equilibrium and manifesting itself as thermal energy, or even kinetic energy, in the material. With a few exceptions related to high-energy photons (such as fluorescence, harmonic generation, photochemical reactions, the photovoltaic effect for ionizing radiations at far ultraviolet, X-ray, and gamma radiation), absorbed electromagnetic radiation simply deposits its energy by heating the material. This happens for infrared, microwave, and radio wave radiation. Intense radio waves can thermally burn living tissue and can cook food. In addition to infrared lasers, sufficiently intense visible and ultraviolet lasers can easily set paper afire. Ionizing radiation creates high-speed electrons in a material and breaks chemical bonds, but after these electrons collide many times with other atoms eventually most of the energy becomes thermal energy all in a tiny fraction of a second. This caveat also applies to UV, even though almost all of it is not ionizing, because UV can damage molecules due to electronic excitation, which is far greater per unit energy than heating effects. Infrared radiation in the spectral distribution of a black body is usually considered a form of heat, since it has an equivalent temperature and is associated with an entropy change per unit of thermal energy. However, "heat" is a technical term in physics and thermodynamics and is often confused with thermal energy. Any type of electromagnetic energy can be transformed into thermal energy in interaction with matter. Thus, any electromagnetic radiation can "heat" (in the sense of increase the thermal energy temperature of) a material, when it is absorbed. The inverse or time-reversed process of absorption is thermal radiation. Much of the thermal energy in matter consists of random motion of charged particles, and this energy can be radiated away from the matter. The resulting radiation may subsequently be absorbed by another piece of matter, with the deposited energy heating the material. The electromagnetic radiation in an opaque cavity at thermal equilibrium is effectively a form of thermal energy, having maximum radiation entropy. Biological effects Bioelectromagnetics is the study of the interactions and effects of EM radiation on living organisms. The effects of electromagnetic radiation upon living cells, including those in humans, depends upon the radiation's power and frequency. For low-frequency radiation (radio waves to near ultraviolet) the best-understood effects are those due to radiation power alone, acting through heating when radiation is absorbed. For these thermal effects, frequency is important as it affects the intensity of the radiation and penetration into the organism (for example, microwaves penetrate better than infrared). It is widely accepted that low frequency fields that are too weak to cause significant heating could not possibly have any biological effect. Some research suggests that weaker non-thermal electromagnetic fields (including weak ELF magnetic fields, although the latter does not strictly qualify as EM radiation) and modulated RF and microwave fields can have biological effects, though the significance of this is unclear. The World Health Organization has classified radio frequency electromagnetic radiation as Group 2B—possibly carcinogenic. This group contains possible carcinogens such as lead, DDT, and styrene. At higher frequencies (some of visible and beyond), the effects of individual photons begin to become important, as these now have enough energy individually to directly or indirectly damage biological molecules. All UV frequencies have been classed as Group 1 carcinogens by the World Health Organization. Ultraviolet radiation from sun exposure is the primary cause of skin cancer. Thus, at UV frequencies and higher, electromagnetic radiation does more damage to biological systems than simple heating predicts. This is most obvious in the "far" (or "extreme") ultraviolet. UV, with X-ray and gamma radiation, are referred to as ionizing radiation due to the ability of photons of this radiation to produce ions and free radicals in materials (including living tissue). Since such radiation can severely damage life at energy levels that produce little heating, it is considered far more dangerous (in terms of damage-produced per unit of energy, or power) than the rest of the electromagnetic spectrum. The heat ray is an application of EMR that makes use of microwave frequencies to create an unpleasant heating effect in the upper layer of the skin. A publicly known heat ray weapon called the Active Denial System was developed by the US military as an experimental weapon to deny the enemy access to an area. A death ray is a theoretical weapon that delivers heat ray based on electromagnetic energy at levels that are capable of injuring human tissue. An inventor of a death ray, Harry Grindell Matthews, claimed to have lost sight in his left eye while working on his death ray weapon based on a microwave magnetron from the 1920s (a normal microwave oven creates a tissue damaging cooking effect inside the oven at around 2 kV/m). Derivation from electromagnetic theory Electromagnetic waves are predicted by the classical laws of electricity and magnetism, known as Maxwell's equations. There are nontrivial solutions of the homogeneous Maxwell's equations (without charges or currents), describing waves of changing electric and magnetic fields. Beginning with Maxwell's equations in free space: where Besides the trivial solution E = B = 0 {\displaystyle \mathbf {E} =\mathbf {B} =\mathbf {0} } , useful solutions can be derived with the following vector identity, valid for all vectors A {\displaystyle \mathbf {A} } in some vector field: ∇ × ( ∇ × A ) = ∇ ( ∇ ⋅ A ) − ∇ 2 A . {\displaystyle \nabla \times \left(\nabla \times \mathbf {A} \right)=\nabla \left(\nabla \cdot \mathbf {A} \right)-\nabla ^{2}\mathbf {A} .} Taking the curl of the second Maxwell's equation (2) yields: Evaluating the left hand side of (5) with the above identity and simplifying using (1), yields: Evaluating the right hand side of (5) by exchanging the sequence of derivatives and inserting the fourth Maxwell's equation (4), yields: Combining (6) and (7) again, gives a vector-valued differential equation for the electric field, solving the homogeneous Maxwell's equations: ∇ 2 E = μ 0 ε 0 ∂ 2 E ∂ t 2 {\displaystyle \nabla ^{2}\mathbf {E} =\mu _{0}\varepsilon _{0}{\frac {\partial ^{2}\mathbf {E} }{\partial t^{2}}}} Taking the curl of the fourth Maxwell's equation (4) results in a similar differential equation for a magnetic field solving the homogeneous Maxwell's equations: ∇ 2 B = μ 0 ε 0 ∂ 2 B ∂ t 2 . {\displaystyle \nabla ^{2}\mathbf {B} =\mu _{0}\varepsilon _{0}{\frac {\partial ^{2}\mathbf {B} }{\partial t^{2}}}.} Both differential equations have the form of the general wave equation for waves propagating with speed c 0 , {\displaystyle c_{0},} where f {\displaystyle f} is a function of time and location, which gives the amplitude of the wave at some time at a certain location: ∇ 2 f = 1 c 0 2 ∂ 2 f ∂ t 2 {\displaystyle \nabla ^{2}f={\frac {1}{{c_{0}}^{2}}}{\frac {\partial ^{2}f}{\partial t^{2}}}} This is also written as: ◻ f = 0 {\displaystyle \Box f=0} where ◻ {\displaystyle \Box } denotes the so-called d'Alembert operator, which in Cartesian coordinates is given as: ◻ = ∇ 2 − 1 c 0 2 ∂ 2 ∂ t 2 = ∂ 2 ∂ x 2 + ∂ 2 ∂ y 2 + ∂ 2 ∂ z 2 − 1 c 0 2 ∂ 2 ∂ t 2 {\displaystyle \Box =\nabla ^{2}-{\frac {1}{{c_{0}}^{2}}}{\frac {\partial ^{2}}{\partial t^{2}}}={\frac {\partial ^{2}}{\partial x^{2}}}+{\frac {\partial ^{2}}{\partial y^{2}}}+{\frac {\partial ^{2}}{\partial z^{2}}}-{\frac {1}{{c_{0}}^{2}}}{\frac {\partial ^{2}}{\partial t^{2}}}\ } Comparing the terms for the speed of propagation, yields in the case of the electric and magnetic fields: c 0 = 1 μ 0 ε 0 . {\displaystyle c_{0}={\frac {1}{\sqrt {\mu _{0}\varepsilon _{0}}}}.} This is the speed of light in vacuum. Thus Maxwell's equations connect the vacuum permittivity ε 0 {\displaystyle \varepsilon _{0}} , the vacuum permeability μ 0 {\displaystyle \mu _{0}} , and the speed of light, c0, via the above equation. This relationship had been discovered by Wilhelm Eduard Weber and Rudolf Kohlrausch prior to the development of Maxwell's electrodynamics, however Maxwell was the first to produce a field theory consistent with waves traveling at the speed of light. These are only two equations versus the original four, so more information pertains to these waves hidden within Maxwell's equations. A generic vector wave for the electric field has the form E = E 0 f ( k ^ ⋅ x − c 0 t ) {\displaystyle \mathbf {E} =\mathbf {E} _{0}f{\left({\hat {\mathbf {k} }}\cdot \mathbf {x} -c_{0}t\right)}} Here, E 0 {\displaystyle \mathbf {E} _{0}} is a constant vector, f {\displaystyle f} is any second differentiable function, k ^ {\displaystyle {\hat {\mathbf {k} }}} is a unit vector in the direction of propagation, and x {\displaystyle {\mathbf {x} }} is a position vector. f ( k ^ ⋅ x − c 0 t ) {\displaystyle f{\left({\hat {\mathbf {k} }}\cdot \mathbf {x} -c_{0}t\right)}} is a generic solution to the wave equation. In other words, ∇ 2 f ( k ^ ⋅ x − c 0 t ) = 1 c 0 2 ∂ 2 ∂ t 2 f ( k ^ ⋅ x − c 0 t ) , {\displaystyle \nabla ^{2}f{\left({\hat {\mathbf {k} }}\cdot \mathbf {x} -c_{0}t\right)}={\frac {1}{{c_{0}}^{2}}}{\frac {\partial ^{2}}{\partial t^{2}}}f{\left({\hat {\mathbf {k} }}\cdot \mathbf {x} -c_{0}t\right)},} for a generic wave traveling in the k ^ {\displaystyle {\hat {\mathbf {k} }}} direction. From the first of Maxwell's equations, we get ∇ ⋅ E = k ^ ⋅ E 0 f ′ ( k ^ ⋅ x − c 0 t ) = 0 {\displaystyle \nabla \cdot \mathbf {E} ={\hat {\mathbf {k} }}\cdot \mathbf {E} _{0}f'{\left({\hat {\mathbf {k} }}\cdot \mathbf {x} -c_{0}t\right)}=0} Thus, E ⋅ k ^ = 0 {\displaystyle \mathbf {E} \cdot {\hat {\mathbf {k} }}=0} which implies that the electric field is orthogonal to the direction the wave propagates. The second of Maxwell's equations yields the magnetic field, namely, ∇ × E = k ^ × E 0 f ′ ( k ^ ⋅ x − c 0 t ) = − ∂ B ∂ t {\displaystyle \nabla \times \mathbf {E} ={\hat {\mathbf {k} }}\times \mathbf {E} _{0}f'{\left({\hat {\mathbf {k} }}\cdot \mathbf {x} -c_{0}t\right)}=-{\frac {\partial \mathbf {B} }{\partial t}}} Thus, B = 1 c 0 k ^ × E {\displaystyle \mathbf {B} ={\frac {1}{c_{0}}}{\hat {\mathbf {k} }}\times \mathbf {E} } The remaining equations will be satisfied by this choice of E , B {\displaystyle \mathbf {E} ,\mathbf {B} } . The electric and magnetic field waves in the far-field travel at the speed of light. They have a special restricted orientation and proportional magnitudes, E 0 = c 0 B 0 {\displaystyle E_{0}=c_{0}B_{0}} , which can be seen immediately from the Poynting vector. The electric field, magnetic field, and direction of wave propagation are all orthogonal, and the wave propagates in the same direction as E × B {\displaystyle \mathbf {E} \times \mathbf {B} } . Also E and B far-fields in free space, which as wave solutions depend primarily on these two Maxwell's equations to remain in phase with each other. This is guaranteed since the generic wave solution is first order in both space and time, and the curl operator on one side of these equations results in first-order spatial derivatives of the wave solution, while the time-derivative on the other side of the equations, which gives the other field, is first-order in time, resulting in the same phase shift for both fields in each mathematical operation. From the viewpoint of an electromagnetic wave traveling forward, the electric field might be oscillating up and down, while the magnetic field oscillates right and left. This picture can be rotated with the electric field oscillating right and left and the magnetic field oscillating down and up. This is a different solution that is traveling in the same direction. This arbitrariness in the orientation with respect to propagation direction is known as polarization. On a quantum level, it is described as photon polarization. The direction of the polarization is defined as the direction of the electric field. More general forms of the second-order wave equations given above are available, allowing for both non-vacuum propagation media and sources. Many competing derivations exist, all with varying levels of approximation and intended applications. One very general example is a form of the electric field equation, which was factorized into a pair of explicitly directional wave equations, and then efficiently reduced into a single uni-directional wave equation by means of a simple slow-evolution approximation. See also References Further reading External links |
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[SOURCE: https://en.wikipedia.org/wiki/Gun_Game] | [TOKENS: 751] |
Contents Gun Game Gun Game is a multiplayer video game mode first introduced as a Counter-Strike mod. It was later adapted in other first-person shooters, and became an official mode of the same name in the Call of Duty series; Counter-Strike: Global Offensive and Counter-Strike 2 (under the name "Arms Race"); and Valorant (under the name "Escalation"), among other games. A single-player adaptation of Gun Game with close-combat weapons was modded into Dark Souls. The mode is a form of deathmatch or team deathmatch in which players attempt to kill random opponents, but with the added twist that each time the player scores a kill, their gun is immediately replaced with a more powerful one, cycling through the game's entire arsenal from weakest to strongest. The mode has been praised by critics as enjoyable and increasing the appeal of games that contain it due to the brevity of each Gun Game round, though it is noted to suffer more than typical game modes from players who AFK, becoming easy targets and potentially stacking the game towards otherwise worse players. Description At the beginning of a Gun Game round, all players start with an equally weak weapon. Defeating an enemy causes the player's gun to increase in tier, while a player who is killed has their progress reset when they respawn. Later guns are usually stronger, but may be harder to use, such as sniper rifles. Reaching the highest tier causes the player's gun to be replaced with a combat knife; scoring a kill with the knife causes that player to win, and the entire game to restart. The arenas used for the mode are typically small and symmetrical, so neither side has an advantage. Reception Ben Kidson of PCGamesN praised the addition of Arms Race to Counter-Strike: Global Offensive, describing default Counter-Strike as a "long slog" and saying that Gun Game was different due to the near-immediate respawn of the player as opposed to the typical permadeath. Also commenting on the game's lack of gun purchasing, he called it "oddly liberating". Craig Pearson of Rock Paper Shotgun described Arms Race as "if someone accidentally tumble-dried Counter-Strike". Wesley Yin-Poole of Eurogamer described Call of Duty: WWII's version of Gun Game as "especially awesome", but noted that it had a major problem with AFK players, who are encouraged to "play" through as many rounds as possible as part of the game's Special Order incentives and find Gun Game the quickest way to do so, calling on the game's developers to punish such players. Imogen Beckhelling, also of Rock Paper Shotgun, called Valorant's Escalation mode "exactly the sort of game I crave inbetween the usual tense shoot-outs", noting that it not only included the game's typical weapons, but also randomized special abilities various agents were able to use, describing the result as "brilliant chaos" and "fab", but wanting it to be even more chaotic. The Gun Game of Call of Duty: Black Ops Cold War was described by Jeremy Peel of PC Gamer as "a mode that might be older than some of Cold War’s players", with "a challenging curve" due to the later guns being sniper rifles, but resulting in "one of the finest highs" in the game when the player wins. Edwin Evans-Thirlwell, also from Rock Paper Shotgun, said that Gun Game was the "bestest-best game mode". Legacy Dark Souls received a Gun Game mod without the actual guns, which gives the player XP whenever they attack an enemy, leveling up their weapon as long as their character does not die. It also includes special bonus weapon drops from defeating bosses. References |
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[SOURCE: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero] | [TOKENS: 7584] |
Contents Rounding Rounding or rounding off is the process of adjusting a number to an approximate, more convenient value, often with a shorter or simpler representation. For example, replacing $23.4476 with $23.45, the fraction 312/937 with 1/3, or the expression √2 with 1.414. Rounding is often done to obtain a value that is easier to report and communicate than the original. Rounding can also be important to avoid misleadingly precise reporting of a computed number, measurement, or estimate; for example, a quantity that was computed as 123456 but is known to be accurate only to within a few hundred units is usually better stated as "about 123500". On the other hand, rounding of exact numbers will introduce some round-off error in the reported result. Rounding is almost unavoidable when reporting many computations – especially when dividing two numbers in integer or fixed-point arithmetic; when computing mathematical functions such as square roots, logarithms, and sines; or when using a floating-point representation with a fixed number of significant digits. In a sequence of calculations, these rounding errors generally accumulate, and in certain ill-conditioned cases they may make the result meaningless. Accurate rounding of transcendental mathematical functions is difficult because the number of extra digits that need to be calculated to resolve whether to round up or down cannot be known in advance. This problem is known as "the table-maker's dilemma". Rounding has many similarities to the quantization that occurs when physical quantities must be encoded by numbers or digital signals. A wavy equals sign (≈) is sometimes used to indicate rounding of exact numbers, e.g. 9.98 ≈ 10. This sign was introduced by Alfred George Greenhill in 1892. Ideal characteristics of rounding methods include: Because it is not usually possible for a method to satisfy all ideal characteristics, many different rounding methods exist. As a general rule, rounding is idempotent; i.e., once a number has been rounded, rounding it again to the same precision will not change its value. Rounding functions are also monotonic; i.e., rounding two numbers to the same absolute precision will not exchange their order (but may give the same value). In the general case of a discrete range, they are piecewise constant functions. Types of rounding Typical rounding problems include: Rounding to integer The most basic form of rounding is to replace an arbitrary number by an integer. All the following rounding modes are concrete implementations of an abstract single-argument "round()" procedure. These are true functions (with the exception of those that use randomness). These four methods are called directed rounding to an integer, as the displacements from the original number x to the rounded value y are all directed toward or away from the same limiting value (0, +∞, or −∞). Directed rounding is used in interval arithmetic and is often required in financial calculations. If x is positive, round-down is the same as round-toward-zero, and round-up is the same as round-away-from-zero. If x is negative, round-down is the same as round-away-from-zero, and round-up is the same as round-toward-zero. In any case, if x is an integer, y is just x. Where many calculations are done in sequence, the choice of rounding method can have a very significant effect on the result. A famous instance involved a new index set up by the Vancouver Stock Exchange in 1982. It was initially set at 1000.000 (three decimal places of accuracy), and after 22 months had fallen to about 520, although the market appeared to be rising. The problem was caused by the index being recalculated thousands of times daily, and always being truncated (rounded down) to 3 decimal places, in such a way that the rounding errors accumulated. Recalculating the index for the same period using rounding to the nearest thousandth rather than truncation corrected the index value from 524.811 up to 1098.892. For the examples below, sgn(x) refers to the sign function applied to the original number, x. One may round down (or take the floor, or round toward negative infinity): y is the largest integer that does not exceed x. For example, 23.7 gets rounded to 23, and −23.2 gets rounded to −24. One may also round up (or take the ceiling, or round toward positive infinity): y is the smallest integer that is not less than x. For example, 23.2 gets rounded to 24, and −23.7 gets rounded to −23. One may also round toward zero (or truncate, or round away from infinity): y is the integer that is closest to x such that it is between 0 and x (included); i.e. y is the integer part of x, without its fraction digits. For example, 23.7 gets rounded to 23, and −23.7 gets rounded to −23. One may also round away from zero (or round toward infinity): y is the integer that is closest to 0 (or equivalently, to x) such that x is between 0 and y (included). For example, 23.2 gets rounded to 24, and −23.2 gets rounded to −24. These six methods are called rounding to the nearest integer. Rounding a number x to the nearest integer requires some tie-breaking rule for those cases when x is exactly half-way between two integers – that is, when the fraction part of x is exactly 0.5. If it were not for the 0.5 fractional parts, the round-off errors introduced by the round to nearest method would be symmetric: for every fraction that gets rounded down (such as 0.268), there is a complementary fraction (namely, 0.732) that gets rounded up by the same amount. When rounding a large set of fixed-point numbers with uniformly distributed fractional parts, the rounding errors by all values, with the omission of those having 0.5 fractional part, would statistically compensate each other. This means that the expected (average) value of the rounded numbers is equal to the expected value of the original numbers when numbers with fractional part 0.5 from the set are removed. In practice, floating-point numbers are typically used, which have even more computational nuances because they are not equally spaced. One may round half up (or round half toward positive infinity), a tie-breaking rule that is widely used in many disciplines.[citation needed] That is, half-way values of x are always rounded up. If the fractional part of x is exactly 0.5, then y = x + 0.5 For example, 23.5 gets rounded to 24, and −23.5 gets rounded to −23. Some programming languages (such as Java and Python) use "half up" to refer to round half away from zero rather than round half toward positive infinity. This method only requires checking one digit to determine rounding direction in two's complement and similar representations. One may also round half down (or round half toward negative infinity) as opposed to the more common round half up. If the fractional part of x is exactly 0.5, then y = x − 0.5 For example, 23.5 gets rounded to 23, and −23.5 gets rounded to −24. Some programming languages (such as Java and Python) use "half down" to refer to round half toward zero rather than round half toward negative infinity. One may also round half toward zero (or round half away from infinity) as opposed to the conventional round half away from zero. If the fractional part of x is exactly 0.5, then y = x − 0.5 if x is positive, and y = x + 0.5 if x is negative. For example, 23.5 gets rounded to 23, and −23.5 gets rounded to −23. This method treats positive and negative values symmetrically, and therefore is free of overall positive/negative bias if the original numbers are positive or negative with equal probability. It does, however, still have bias toward zero. One may also round half away from zero (or round half toward infinity), a tie-breaking rule that is commonly taught and used, namely: If the fractional part of x is exactly 0.5, then y = x + 0.5 if x is positive, and y = x − 0.5 if x is negative. For example, 23.5 gets rounded to 24, and −23.5 gets rounded to −24. This can be more efficient on computers that use sign-magnitude representation for the values to be rounded, because only the first omitted digit needs to be considered to determine if it rounds up or down. This is one method used when rounding to significant figures due to its simplicity. This method, also known as commercial rounding,[citation needed] treats positive and negative values symmetrically, and therefore is free of overall positive/negative bias if the original numbers are positive or negative with equal probability. It does, however, still have bias away from zero. It is often used for currency conversions and price roundings (when the amount is first converted into the smallest significant subdivision of the currency, such as cents of a euro) as it is easy to explain by just considering the first fractional digit, independently of supplementary precision digits or sign of the amount (for strict equivalence between the paying and recipient of the amount). One may also round half to even, a tie-breaking rule without positive/negative bias and without bias toward/away from zero. By this convention, if the fractional part of x is 0.5, then y is the even integer nearest to x. Thus, for example, 23.5 becomes 24, as does 24.5; however, −23.5 becomes −24, as does −24.5. This function minimizes the expected error when summing over rounded figures, regardless of the inputs being mostly positive or mostly negative, provided they are neither mostly even nor mostly odd. This variant of the round-to-nearest method is also called convergent rounding, statistician's rounding, Dutch rounding, Gaussian rounding, odd–even rounding, or bankers' rounding. This is the default rounding mode used in IEEE 754 operations for results in binary floating-point formats. By eliminating bias, repeated addition or subtraction of independent numbers, as in a one-dimensional random walk, will give a rounded result with an error that tends to grow in proportion to the square root of the number of operations rather than linearly. However, this rule distorts the distribution by increasing the probability of evens relative to odds. That is why this rule is for situations where sums are more important than distribution.[clarification needed] One may also round half to odd, a similar tie-breaking rule to round half to even. In this approach, if the fractional part of x is 0.5, then y is the odd integer nearest to x. Thus, for example, 23.5 becomes 23, as does 22.5; while −23.5 becomes −23, as does −22.5. This method is also free from positive/negative bias and bias toward/away from zero, provided the numbers to be rounded are neither mostly even nor mostly odd. It also shares the round half to even property of distorting the original distribution, as it increases the probability of odds relative to evens. It was the method used for bank balances in the United Kingdom when it decimalized its currency[clarification needed]. This variant is almost never used in computations, except in situations where one wants to avoid increasing the scale of floating-point numbers, which have a limited exponent range. With round half to even, a non-infinite number would round to infinity, and a small denormal value would round to a normal non-zero value. Effectively, this mode prefers preserving the existing scale of tie numbers, avoiding out-of-range results when possible for numeral systems of even radix (such as binary and decimal).[clarification needed (see talk)]. One method, more obscure than most, is to alternate direction when rounding a number with 0.5 fractional part. All others are rounded to the closest integer. Whenever the fractional part is 0.5, alternate rounding up or down: for the first occurrence of a 0.5 fractional part, round up, for the second occurrence, round down, and so on. Alternatively, the first 0.5 fractional part rounding can be determined by a random seed. "Up" and "down" can be any two rounding methods that oppose each other - toward and away from positive infinity or toward and away from zero. If occurrences of 0.5 fractional parts occur significantly more than a restart of the occurrence "counting", then it is effectively bias free. With guaranteed zero bias, it is useful if the numbers are to be summed or averaged. If the fractional part of x is 0.5, choose y randomly between x + 0.5 and x − 0.5, with equal probability. All others are rounded to the closest integer. Like round-half-to-even and round-half-to-odd, this rule is essentially free of overall bias, but it is also fair among even and odd y values. An advantage over alternate tie-breaking is that the last direction of rounding on the 0.5 fractional part does not have to be "remembered". Rounding as follows to one of the closest integer toward negative infinity and the closest integer toward positive infinity, with a probability dependent on the proximity is called stochastic rounding and will give an unbiased result on average. For example, 1.6 would be rounded to 1 with probability 0.4 and to 2 with probability 0.6. Stochastic rounding can be accurate in a way that a rounding function can never be. For example, suppose one started with 0 and added 0.3 to that one hundred times while rounding the running total between every addition. The result would be 0 with regular rounding, but with stochastic rounding, the expected result would be 30, which is the same value obtained without rounding. This can be useful in machine learning where the training may use low precision arithmetic iteratively. Stochastic rounding is also a way to achieve 1-dimensional dithering. Rounding to other values The most common type of rounding is to round to an integer; or, more generally, to an integer multiple of some increment – such as rounding to whole tenths of seconds, hundredths of a dollar, to whole multiples of 1/2 or 1/8 inch, to whole dozens or thousands, etc. In general, rounding a number x to a multiple of some specified positive value m entails the following steps: For example, rounding x = 2.1784 dollars to whole cents (i.e., to a multiple of 0.01) entails computing 2.1784 / 0.01 = 217.84, then rounding that to 218, and finally computing 218 × 0.01 = 2.18. When rounding to a predetermined number of significant digits, the increment m depends on the magnitude of the number to be rounded (or of the rounded result). The increment m is normally a finite fraction in whatever numeral system is used to represent the numbers. For display to humans, that usually means the decimal numeral system (that is, m is an integer times a power of 10, like 1/1000 or 25/100). For intermediate values stored in digital computers, it often means the binary numeral system (m is an integer times a power of 2). The abstract single-argument "round()" function that returns an integer from an arbitrary real value has at least a dozen distinct concrete definitions presented in the rounding to integer section. The abstract two-argument "roundToMultiple()" function is formally defined here, but in many cases it is used with the implicit value m = 1 for the increment and then reduces to the equivalent abstract single-argument function, with also the same dozen distinct concrete definitions. Rounding to a specified power is very different from rounding to a specified multiple; for example, it is common in computing to need to round a number to a whole power of 2. The steps, in general, to round a positive number x to a power of some positive number b other than 1, are: Many of the caveats applicable to rounding to a multiple are applicable to rounding to a power. In the chromatic "twelve-tone" scale of music, 3⁄2 is rounded to 27/12 (a fifth), 4⁄3 is rounded to 25/12 (a fourth), 5⁄4 is rounded to 24/12 (a major third), 6⁄5 is rounded to 23/12 (a minor third), and 9⁄8 is rounded to 22/12 (a diminished third). This type of rounding, which is also named rounding to a logarithmic scale, is a variant of rounding to a specified power. Rounding on a logarithmic scale is accomplished by taking the log of the amount and doing normal rounding to the nearest value on the log scale. For example, resistors are supplied with preferred numbers on a logarithmic scale. In particular, for resistors with a 10% accuracy, they are supplied with nominal values 100, 120, 150, 180, 220, etc. rounded to multiples of 10 (E12 series). If a calculation indicates a resistor of 165 ohms is required then log(150) = 2.176, log(165) = 2.217 and log(180) = 2.255. The logarithm of 165 is closer to the logarithm of 180 therefore a 180 ohm resistor would be the first choice if there are no other considerations. Whether a value x ∈ (a, b) rounds to a or b depends upon whether the squared value x2 is greater than or less than the product ab. The value 165 rounds to 180 in the resistors example because 1652 = 27225 is greater than 150 × 180 = 27000. In floating-point arithmetic, rounding aims to turn a given value x into a value y with a specified number of significant digits. In other words, y should be a multiple of a number m that depends on the magnitude of x. The number m is a power of the base (usually 2 or 10) of the floating-point representation. Apart from this detail, all the variants of rounding discussed above apply to the rounding of floating-point numbers as well. The algorithm for such rounding is presented in the Scaled rounding section above, but with a constant scaling factor s = 1, and an integer base b > 1. Where the rounded result would overflow the result for a directed rounding is either the appropriate signed infinity when "rounding away from zero", or the highest representable positive finite number (or the lowest representable negative finite number if x is negative), when "rounding toward zero". The result of an overflow for the usual case of round to nearest is always the appropriate infinity. In some contexts it is desirable to round a given number x to a "neat" fraction – that is, the nearest fraction y = m/n whose numerator m and denominator n do not exceed a given maximum. This problem is fairly distinct from that of rounding a value to a fixed number of decimal or binary digits, or to a multiple of a given unit m. This problem is related to Farey sequences, the Stern–Brocot tree, and continued fractions. Finished lumber, writing paper, electronic components, and many other products are usually sold in only a few standard values. Many design procedures describe how to calculate an approximate value, and then "round" to some standard size using phrases such as "round down to nearest standard value", "round up to nearest standard value", or "round to nearest standard value". When a set of preferred values is equally spaced on a logarithmic scale, choosing the closest preferred value to any given value can be seen as a form of scaled rounding. Such rounded values can be directly calculated. More general rounding rules can separate values at arbitrary break points, used for example in data binning. A related mathematically formalized tool is signpost sequences, which use notions of distance other than the simple difference – for example, a sequence may round to the integer with the smallest relative (percent) error. Rounding in other contexts When digitizing continuous signals, such as sound waves, the overall effect of a number of measurements is more important than the accuracy of each individual measurement. In these circumstances, dithering, and a related technique, error diffusion, are normally used. A related technique called pulse-width modulation is used to achieve analog type output from an inertial device by rapidly pulsing the power with a variable duty cycle. Delta-sigma modulation is commonly used for converting between real-world signals and digital signals, which allows control of the frequency statistics of quantization. Error diffusion tries to ensure the error, on average, is minimized. When dealing with a gentle slope from one to zero, the output would be zero for the first few terms until the sum of the error and the current value becomes greater than 0.5, in which case a 1 is output and the difference subtracted from the error so far. Floyd–Steinberg dithering is a popular error diffusion procedure when digitizing images. As a one-dimensional example, suppose the numbers 0.9677, 0.9204, 0.7451, and 0.3091 occur in order and each is to be rounded to a multiple of 0.01. In this case the cumulative sums, 0.9677, 1.8881 = 0.9677 + 0.9204, 2.6332 = 0.9677 + 0.9204 + 0.7451, and 2.9423 = 0.9677 + 0.9204 + 0.7451 + 0.3091, are each rounded to a multiple of 0.01: 0.97, 1.89, 2.63, and 2.94. The first of these and the differences of adjacent values give the desired rounded values: 0.97, 0.92 = 1.89 − 0.97, 0.74 = 2.63 − 1.89, and 0.31 = 2.94 − 2.63. Monte Carlo arithmetic is a technique in Monte Carlo methods where the rounding is randomly up or down. Stochastic rounding can be used for Monte Carlo arithmetic, but in general, just rounding up or down with equal probability is more often used. Repeated runs will give a random distribution of results which can indicate the stability of the computation. It is possible to use rounded arithmetic to evaluate the exact value of a function with integer domain and range. For example, if an integer n is known to be a perfect square, its square root can be computed by converting n to a floating-point value z, computing the approximate square root x of z with floating point, and then rounding x to the nearest integer y. If n is not too big, the floating-point round-off error in x will be less than 0.5, so the rounded value y will be the exact square root of n. This is essentially why slide rules could be used for exact arithmetic. Rounding a number twice in succession to different levels of precision, with the latter precision being coarser, is not guaranteed to give the same result as rounding once to the final precision except in the case of directed rounding.[nb 2] For instance, rounding 9.46 to the nearest tenth gives 9.5, and then 10 when rounding to the nearest integer using rounding half to even, but would give 9 when rounded directly using the same method. Borman and Chatfield discuss the implications of double rounding when comparing data rounded to one decimal place to specification limits expressed using integers. In Martinez v. Allstate and Sendejo v. Farmers, litigated between 1995 and 1997, the insurance companies argued that double rounding premiums was permissible and in fact required. The US courts ruled against the insurance companies and ordered them to adopt rules to ensure single rounding. Some computer languages and the IEEE 754-2008 standard dictate that in straightforward calculations the result should not be rounded twice. This has been a particular problem with Java, as it is designed to be run identically on different machines; special programming tricks have had to be used to achieve this with x87 floating point. The Java language was changed to allow different results where the difference does not matter and require a strictfp qualifier to be used when the results have to conform accurately; strict floating point was restored in Java 17. In some algorithms, an intermediate result is computed in a larger precision, then must be rounded to the final precision. Double rounding can be avoided by choosing an adequate rounding for the intermediate computation. This consists in avoiding to round to midpoints for the final rounding (except when the midpoint is exact). In binary arithmetic, the idea is to round the result toward zero, and set the least significant bit to 1 if the rounded result is inexact; this rounding is called sticky rounding. Equivalently, it consists in returning the intermediate result when it is exactly representable, and the nearest floating-point number with an odd significand otherwise; this is why it is also known as rounding to odd. A concrete implementation of this approach, for binary and decimal arithmetic, is implemented as Rounding to prepare for shorter precision. This rounding mode is used to avoid getting a potentially wrong result after multiple roundings. This can be achieved if all roundings except the final one are done using rounding to prepare for shorter precision ("RPSP"), and only the final rounding uses the externally requested mode. With decimal arithmetic, final digits of 0 and 5 are avoided when the input is not representable exactly; if there is a choice between numbers with the least significant digit 0 or 1, 4 or 5, 5 or 6, 9 or 0, then the digit different from 0 or 5 shall be selected; otherwise, the choice is arbitrary. IBM defines that, in the latter case, a digit with the smaller magnitude shall be selected. RPSP can be applied with the step between two consequent roundings as small as a single digit (for example, rounding to 1/10 can be applied after rounding to 1/100). For example, when rounding to integer, In the example from "Double rounding" section, rounding 9.46 to one decimal gives 9.4, which rounding to integer in turn gives 9. With binary arithmetic, this rounding is also called "round to odd" (not to be confused with "round half to odd"). For example, when rounding to 1/4 (0.01 in binary), For correct results with binary arithmetic, each rounding step must remove at least 2 binary digits, otherwise, wrong results may appear. For example, If the erroneous middle step is removed, the final rounding to integer rounds 3.25 to the correct value of 3. RPSP is implemented in hardware in IBM zSeries and pSeries. In Python module "Decimal", Tcl module "math", Haskell package "decimal-arithmetic", and possibly others, this mode is called ROUND_05UP or round05up. William M. Kahan coined the term "The Table-Maker's Dilemma" for the unknown cost of rounding transcendental functions: Nobody knows how much it would cost to compute yw correctly rounded for every two floating-point arguments at which it does not over/underflow. Instead, reputable math libraries compute elementary transcendental functions mostly within slightly more than half an ulp and almost always well within one ulp. Why can't yw be rounded within half an ulp like SQRT? Because nobody knows how much computation it would cost... No general way exists to predict how many extra digits will have to be carried to compute a transcendental expression and round it correctly to some preassigned number of digits. Even the fact (if true) that a finite number of extra digits will ultimately suffice may be a deep theorem. The IEEE 754 floating-point standard guarantees that add, subtract, multiply, divide, fused multiply–add, square root, and floating-point remainder will give the correctly rounded result of the infinite-precision operation. No such guarantee was given in the 1985 standard for more complex functions and they are typically only accurate to within the last bit at best. However, the 2008 standard guarantees that conforming implementations will give correctly rounded results which respect the active rounding mode; implementation of the functions, however, is optional. Using the Gelfond–Schneider theorem and Lindemann–Weierstrass theorem, many of the standard elementary functions can be proved to return transcendental results, except on some well-known arguments; therefore, from a theoretical point of view, it is always possible to correctly round such functions. However, for an implementation of such a function, determining a limit for a given precision on how accurate results need to be computed, before a correctly rounded result can be guaranteed, may demand a lot of computation time or may be out of reach. In practice, when this limit is not known (or only a very large bound is known), some decision has to be made in the implementation (see below); but according to a probabilistic model, correct rounding can be satisfied with a very high probability when using an intermediate accuracy of up to twice the number of digits of the target format plus some small constant (after taking special cases into account). Some programming packages offer correct rounding. The GNU MPFR package gives correctly rounded arbitrary precision results. Some other libraries implement elementary functions with correct rounding in IEEE 754 double precision (binary64): There exist computable numbers for which a rounded value can never be determined no matter how many digits are calculated. Specific instances cannot be given but this follows from the undecidability of the halting problem. For instance, if Goldbach's conjecture is true but unprovable, then the result of rounding the following value, n, up to the next integer cannot be determined: either n=1+10−k where k is the first even number greater than 4 which is not the sum of two primes, or n=1 if there is no such number. The rounded result is 2 if such a number k exists and 1 otherwise. The value before rounding can however be approximated to any given precision even if the conjecture is unprovable. Rounding can adversely affect a string search for a number. For example, π rounded to four digits is "3.1416" but a simple search for this string will not discover "3.14159" or any other value of π rounded to more than four digits. In contrast, truncation does not suffer from this problem; for example, a simple string search for "3.1415", which is π truncated to four digits, will discover values of π truncated to more than four digits. History The concept of rounding is very old, perhaps older than the concept of division itself. Some ancient clay tablets found in Mesopotamia contain tables with rounded values of reciprocals and square roots in base 60. Rounded approximations to π, the length of the year, and the length of the month are also ancient—see base 60 examples. The round-half-to-even method has served as American Standard Z25.1 and ASTM standard E-29 since 1940. The origin of the terms unbiased rounding and statistician's rounding are fairly self-explanatory. In the 1906 fourth edition of Probability and Theory of Errors Robert Simpson Woodward called this "the computer's rule", indicating that it was then in common use by human computers who calculated mathematical tables. For example, it was recommended in Simon Newcomb's c. 1882 book Logarithmic and Other Mathematical Tables. Lucius Tuttle's 1916 Theory of Measurements called it a "universally adopted rule" for recording physical measurements. Churchill Eisenhart indicated the practice was already "well established" in data analysis by the 1940s. The origin of the term bankers' rounding remains more obscure. If this rounding method was ever a standard in banking, the evidence has proved extremely difficult to find. To the contrary, section 2 of the European Commission report The Introduction of the Euro and the Rounding of Currency Amounts suggests that there had previously been no standard approach to rounding in banking; and it specifies that "half-way" amounts should be rounded up. Until the 1980s, the rounding method used in floating-point computer arithmetic was usually fixed by the hardware, poorly documented, inconsistent, and different for each brand and model of computer. This situation changed after the IEEE 754 floating-point standard was adopted by most computer manufacturers. The standard allows the user to choose among several rounding modes, and in each case specifies precisely how the results should be rounded. These features made numerical computations more predictable and machine-independent, and made possible the efficient and consistent implementation of interval arithmetic. Currently, much research tends to round to multiples of 5 or 2. For example, Jörg Baten used age heaping in many studies, to evaluate the numeracy level of ancient populations. He came up with the ABCC Index, which enables the comparison of the numeracy among regions possible without any historical sources where the population literacy was measured. Rounding functions in programming languages Most programming languages provide functions or special syntax to round fractional numbers in various ways. The earliest numeric languages, such as Fortran and C, would provide only one method, usually truncation (toward zero). This default method could be implied in certain contexts, such as when assigning a fractional number to an integer variable, or using a fractional number as an index of an array. Other kinds of rounding had to be programmed explicitly; for example, rounding a positive number to the nearest integer could be implemented by adding 0.5 and truncating. In the last decades, however, the syntax and the standard libraries of most languages have commonly provided at least the four basic rounding functions (up, down, to nearest, and toward zero). The tie-breaking method can vary depending on the language and version or might be selectable by the programmer. Several languages follow the lead of the IEEE 754 floating-point standard, and define these functions as taking a double-precision float argument and returning the result of the same type, which then may be converted to an integer if necessary. This approach may avoid spurious overflows because floating-point types have a larger range than integer types. Some languages, such as PHP, provide functions that round a value to a specified number of decimal digits (e.g., from 4321.5678 to 4321.57 or 4300). In addition, many languages provide a printf or similar string formatting function, which allows one to convert a fractional number to a string, rounded to a user-specified number of decimal places (the precision). On the other hand, truncation (round to zero) is still the default rounding method used by many languages, especially for the division of two integer values. In contrast, CSS and SVG do not define any specific maximum precision for numbers and measurements, which they treat and expose in their DOM and in their IDL interface as strings as if they had infinite precision, and do not discriminate between integers and floating-point values; however, the implementations of these languages will typically convert these numbers into IEEE 754 double-precision floating-point values before exposing the computed digits with a limited precision (notably within standard JavaScript or ECMAScript interface bindings). Other rounding standards Some disciplines or institutions have issued standards or directives for rounding. In a guideline issued in mid-1966, the U.S. Office of the Federal Coordinator for Meteorology determined that weather data should be rounded to the nearest round number, with the "round half up" tie-breaking rule. For example, 1.5 rounded to integer should become 2, and −1.5 should become −1. Prior to that date, the tie-breaking rule was "round half away from zero". Some meteorologists may write "−0" to indicate a temperature between 0.0 and −0.5 degrees (exclusive) that was rounded to an integer. This notation is used when the negative sign is considered important, no matter how small is the magnitude; for example, when rounding temperatures in the Celsius scale, where below zero indicates freezing.[citation needed] See also Notes References External links |
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[SOURCE: https://en.wikipedia.org/wiki/Lod#cite_ref-34] | [TOKENS: 4733] |
Contents Lod Lod (Hebrew: לוד, fully vocalized: לֹד), also known as Lydda (Ancient Greek: Λύδδα) and Lidd (Arabic: اللِّدّ, romanized: al-Lidd, or اللُّدّ, al-Ludd), is a city 15 km (9+1⁄2 mi) southeast of Tel Aviv and 40 km (25 mi) northwest of Jerusalem in the Central District of Israel. It is situated between the lower Shephelah on the east and the coastal plain on the west. The city had a population of 90,814 in 2023. Lod has been inhabited since at least the Neolithic period. It is mentioned a few times in the Hebrew Bible and in the New Testament. Between the 5th century BCE and up until the late Roman period, it was a prominent center for Jewish scholarship and trade. Around 200 CE, the city became a Roman colony and was renamed Diospolis (Ancient Greek: Διόσπολις, lit. 'city of Zeus'). Tradition identifies Lod as the 4th century martyrdom site of Saint George; the Church of Saint George and Mosque of Al-Khadr located in the city is believed to have housed his remains. Following the Arab conquest of the Levant, Lod served as the capital of Jund Filastin; however, a few decades later, the seat of power was transferred to Ramla, and Lod slipped in importance. Under Crusader rule, the city was a Catholic diocese of the Latin Church and it remains a titular see to this day.[citation needed] Lod underwent a major change in its population in the mid-20th century. Exclusively Palestinian Arab in 1947, Lod was part of the area designated for an Arab state in the United Nations Partition Plan for Palestine; however, in July 1948, the city was occupied by the Israel Defense Forces, and most of its Arab inhabitants were expelled in the Palestinian expulsion from Lydda and Ramle. The city was largely resettled by Jewish immigrants, most of them expelled from Arab countries. Today, Lod is one of Israel's mixed cities, with an Arab population of 30%. Lod is one of Israel's major transportation hubs. The main international airport, Ben Gurion Airport, is located 8 km (5 miles) north of the city. The city is also a major railway and road junction. Religious references The Hebrew name Lod appears in the Hebrew Bible as a town of Benjamin, founded along with Ono by Shamed or Shamer (1 Chronicles 8:12; Ezra 2:33; Nehemiah 7:37; 11:35). In Ezra 2:33, it is mentioned as one of the cities whose inhabitants returned after the Babylonian captivity. Lod is not mentioned among the towns allocated to the tribe of Benjamin in Joshua 18:11–28. The name Lod derives from a tri-consonantal root not extant in Northwest Semitic, but only in Arabic (“to quarrel; withhold, hinder”). An Arabic etymology of such an ancient name is unlikely (the earliest attestation is from the Achaemenid period). In the New Testament, the town appears in its Greek form, Lydda, as the site of Peter's healing of Aeneas in Acts 9:32–38. The city is also mentioned in an Islamic hadith as the location of the battlefield where the false messiah (al-Masih ad-Dajjal) will be slain before the Day of Judgment. History The first occupation dates to the Neolithic in the Near East and is associated with the Lodian culture. Occupation continued in the Levant Chalcolithic. Pottery finds have dated the initial settlement in the area now occupied by the town to 5600–5250 BCE. In the Early Bronze, it was an important settlement in the central coastal plain between the Judean Shephelah and the Mediterranean coast, along Nahal Ayalon. Other important nearby sites were Tel Dalit, Tel Bareqet, Khirbat Abu Hamid (Shoham North), Tel Afeq, Azor and Jaffa. Two architectural phases belong to the late EB I in Area B. The first phase had a mudbrick wall, while the late phase included a circulat stone structure. Later excavations have produced an occupation later, Stratum IV. It consists of two phases, Stratum IVb with mudbrick wall on stone foundations and rounded exterior corners. In Stratum IVa there was a mudbrick wall with no stone foundations, with imported Egyptian potter and local pottery imitations. Another excavations revealed nine occupation strata. Strata VI-III belonged to Early Bronze IB. The material culture showed Egyptian imports in strata V and IV. Occupation continued into Early Bronze II with four strata (V-II). There was continuity in the material culture and indications of centralized urban planning. North to the tell were scattered MB II burials. The earliest written record is in a list of Canaanite towns drawn up by the Egyptian pharaoh Thutmose III at Karnak in 1465 BCE. From the fifth century BCE until the Roman period, the city was a centre of Jewish scholarship and commerce. According to British historian Martin Gilbert, during the Hasmonean period, Jonathan Maccabee and his brother, Simon Maccabaeus, enlarged the area under Jewish control, which included conquering the city. The Jewish community in Lod during the Mishnah and Talmud era is described in a significant number of sources, including information on its institutions, demographics, and way of life. The city reached its height as a Jewish center between the First Jewish-Roman War and the Bar Kokhba revolt, and again in the days of Judah ha-Nasi and the start of the Amoraim period. The city was then the site of numerous public institutions, including schools, study houses, and synagogues. In 43 BC, Cassius, the Roman governor of Syria, sold the inhabitants of Lod into slavery, but they were set free two years later by Mark Antony. During the First Jewish–Roman War, the Roman proconsul of Syria, Cestius Gallus, razed the town on his way to Jerusalem in Tishrei 66 CE. According to Josephus, "[he] found the city deserted, for the entire population had gone up to Jerusalem for the Feast of Tabernacles. He killed fifty people whom he found, burned the town and marched on". Lydda was occupied by Emperor Vespasian in 68 CE. In the period following the destruction of Jerusalem in 70 CE, Rabbi Tarfon, who appears in many Tannaitic and Jewish legal discussions, served as a rabbinic authority in Lod. During the Kitos War, 115–117 CE, the Roman army laid siege to Lod, where the rebel Jews had gathered under the leadership of Julian and Pappos. Torah study was outlawed by the Romans and pursued mostly in the underground. The distress became so great, the patriarch Rabban Gamaliel II, who was shut up there and died soon afterwards, permitted fasting on Ḥanukkah. Other rabbis disagreed with this ruling. Lydda was next taken and many of the Jews were executed; the "slain of Lydda" are often mentioned in words of reverential praise in the Talmud. In 200 CE, emperor Septimius Severus elevated the town to the status of a city, calling it Colonia Lucia Septimia Severa Diospolis. The name Diospolis ("City of Zeus") may have been bestowed earlier, possibly by Hadrian. At that point, most of its inhabitants were Christian. The earliest known bishop is Aëtius, a friend of Arius. During the following century (200-300CE), it's said that Joshua ben Levi founded a yeshiva in Lod. In December 415, the Council of Diospolis was held here to try Pelagius; he was acquitted. In the sixth century, the city was renamed Georgiopolis after St. George, a soldier in the guard of the emperor Diocletian, who was born there between 256 and 285 CE. The Church of Saint George and Mosque of Al-Khadr is named for him. The 6th-century Madaba map shows Lydda as an unwalled city with a cluster of buildings under a black inscription reading "Lod, also Lydea, also Diospolis". An isolated large building with a semicircular colonnaded plaza in front of it might represent the St George shrine. After the Muslim conquest of Palestine by Amr ibn al-'As in 636 CE, Lod which was referred to as "al-Ludd" in Arabic served as the capital of Jund Filastin ("Military District of Palaestina") before the seat of power was moved to nearby Ramla during the reign of the Umayyad Caliph Suleiman ibn Abd al-Malik in 715–716. The population of al-Ludd was relocated to Ramla, as well. With the relocation of its inhabitants and the construction of the White Mosque in Ramla, al-Ludd lost its importance and fell into decay. The city was visited by the local Arab geographer al-Muqaddasi in 985, when it was under the Fatimid Caliphate, and was noted for its Great Mosque which served the residents of al-Ludd, Ramla, and the nearby villages. He also wrote of the city's "wonderful church (of St. George) at the gate of which Christ will slay the Antichrist." The Crusaders occupied the city in 1099 and named it St Jorge de Lidde. It was briefly conquered by Saladin, but retaken by the Crusaders in 1191. For the English Crusaders, it was a place of great significance as the birthplace of Saint George. The Crusaders made it the seat of a Latin Church diocese, and it remains a titular see. It owed the service of 10 knights and 20 sergeants, and it had its own burgess court during this era. In 1226, Ayyubid Syrian geographer Yaqut al-Hamawi visited al-Ludd and stated it was part of the Jerusalem District during Ayyubid rule. Sultan Baybars brought Lydda again under Muslim control by 1267–8. According to Qalqashandi, Lydda was an administrative centre of a wilaya during the fourteenth and fifteenth century in the Mamluk empire. Mujir al-Din described it as a pleasant village with an active Friday mosque. During this time, Lydda was a station on the postal route between Cairo and Damascus. In 1517, Lydda was incorporated into the Ottoman Empire as part of the Damascus Eyalet, and in the 1550s, the revenues of Lydda were designated for the new waqf of Hasseki Sultan Imaret in Jerusalem, established by Hasseki Hurrem Sultan (Roxelana), the wife of Suleiman the Magnificent. By 1596 Lydda was a part of the nahiya ("subdistrict") of Ramla, which was under the administration of the liwa ("district") of Gaza. It had a population of 241 households and 14 bachelors who were all Muslims, and 233 households who were Christians. They paid a fixed tax-rate of 33,3 % on agricultural products, including wheat, barley, summer crops, vineyards, fruit trees, sesame, special product ("dawalib" =spinning wheels), goats and beehives, in addition to occasional revenues and market toll, a total of 45,000 Akçe. All of the revenue went to the Waqf. In 1051 AH/1641/2, the Bedouin tribe of al-Sawālima from around Jaffa attacked the villages of Subṭāra, Bayt Dajan, al-Sāfiriya, Jindās, Lydda and Yāzūr belonging to Waqf Haseki Sultan. The village appeared as Lydda, though misplaced, on the map of Pierre Jacotin compiled in 1799. Missionary William M. Thomson visited Lydda in the mid-19th century, describing it as a "flourishing village of some 2,000 inhabitants, imbosomed in noble orchards of olive, fig, pomegranate, mulberry, sycamore, and other trees, surrounded every way by a very fertile neighbourhood. The inhabitants are evidently industrious and thriving, and the whole country between this and Ramleh is fast being filled up with their flourishing orchards. Rarely have I beheld a rural scene more delightful than this presented in early harvest ... It must be seen, heard, and enjoyed to be appreciated." In 1869, the population of Ludd was given as: 55 Catholics, 1,940 "Greeks", 5 Protestants and 4,850 Muslims. In 1870, the Church of Saint George was rebuilt. In 1892, the first railway station in the entire region was established in the city. In the second half of the 19th century, Jewish merchants migrated to the city, but left after the 1921 Jaffa riots. In 1882, the Palestine Exploration Fund's Survey of Western Palestine described Lod as "A small town, standing among enclosure of prickly pear, and having fine olive groves around it, especially to the south. The minaret of the mosque is a very conspicuous object over the whole of the plain. The inhabitants are principally Moslim, though the place is the seat of a Greek bishop resident of Jerusalem. The Crusading church has lately been restored, and is used by the Greeks. Wells are found in the gardens...." From 1918, Lydda was under the administration of the British Mandate in Palestine, as per a League of Nations decree that followed the Great War. During the Second World War, the British set up supply posts in and around Lydda and its railway station, also building an airport that was renamed Ben Gurion Airport after the death of Israel's first prime minister in 1973. At the time of the 1922 census of Palestine, Lydda had a population of 8,103 inhabitants (7,166 Muslims, 926 Christians, and 11 Jews), the Christians were 921 Orthodox, 4 Roman Catholics and 1 Melkite. This had increased by the 1931 census to 11,250 (10,002 Muslims, 1,210 Christians, 28 Jews, and 10 Bahai), in a total of 2475 residential houses. In 1938, Lydda had a population of 12,750. In 1945, Lydda had a population of 16,780 (14,910 Muslims, 1,840 Christians, 20 Jews and 10 "other"). Until 1948, Lydda was an Arab town with a population of around 20,000—18,500 Muslims and 1,500 Christians. In 1947, the United Nations proposed dividing Mandatory Palestine into two states, one Jewish state and one Arab; Lydda was to form part of the proposed Arab state. In the ensuing war, Israel captured Arab towns outside the area the UN had allotted it, including Lydda. In December 1947, thirteen Jewish passengers in a seven-car convoy to Ben Shemen Youth Village were ambushed and murdered.In a separate incident, three Jewish youths, two men and a woman were captured, then raped and murdered in a neighbouring village. Their bodies were paraded in Lydda’s principal street. The Israel Defense Forces entered Lydda on 11 July 1948. The following day, under the impression that it was under attack, the 3rd Battalion was ordered to shoot anyone "seen on the streets". According to Israel, 250 Arabs were killed. Other estimates are higher: Arab historian Aref al Aref estimated 400, and Nimr al Khatib 1,700. In 1948, the population rose to 50,000 during the Nakba, as Arab refugees fleeing other areas made their way there. A key event was the Palestinian expulsion from Lydda and Ramle, with the expulsion of 50,000-70,000 Palestinians from Lydda and Ramle by the Israel Defense Forces. All but 700 to 1,056 were expelled by order of the Israeli high command, and forced to walk 17 km (10+1⁄2 mi) to the Jordanian Arab Legion lines. Estimates of those who died from exhaustion and dehydration vary from a handful to 355. The town was subsequently sacked by the Israeli army. Some scholars, including Ilan Pappé, characterize this as ethnic cleansing. The few hundred Arabs who remained in the city were soon outnumbered by the influx of Jews who immigrated to Lod from August 1948 onward, most of them from Arab countries. As a result, Lod became a predominantly Jewish town. After the establishment of the state, the biblical name Lod was readopted. The Jewish immigrants who settled Lod came in waves, first from Morocco and Tunisia, later from Ethiopia, and then from the former Soviet Union. Since 2008, many urban development projects have been undertaken to improve the image of the city. Upscale neighbourhoods have been built, among them Ganei Ya'ar and Ahisemah, expanding the city to the east. According to a 2010 report in the Economist, a three-meter-high wall was built between Jewish and Arab neighbourhoods and construction in Jewish areas was given priority over construction in Arab neighborhoods. The newspaper says that violent crime in the Arab sector revolves mainly around family feuds over turf and honour crimes. In 2010, the Lod Community Foundation organised an event for representatives of bicultural youth movements, volunteer aid organisations, educational start-ups, businessmen, sports organizations, and conservationists working on programmes to better the city. In the 2021 Israel–Palestine crisis, a state of emergency was declared in Lod after Arab rioting led to the death of an Israeli Jew. The Mayor of Lod, Yair Revivio, urged Prime Minister of Israel Benjamin Netanyahu to deploy Israel Border Police to restore order in the city. This was the first time since 1966 that Israel had declared this kind of emergency lockdown. International media noted that both Jewish and Palestinian mobs were active in Lod, but the "crackdown came for one side" only. Demographics In the 19th century and until the Lydda Death March, Lod was an exclusively Muslim-Christian town, with an estimated 6,850 inhabitants, of whom approximately 2,000 (29%) were Christian. According to the Israel Central Bureau of Statistics (CBS), the population of Lod in 2010 was 69,500 people. According to the 2019 census, the population of Lod was 77,223, of which 53,581 people, comprising 69.4% of the city's population, were classified as "Jews and Others", and 23,642 people, comprising 30.6% as "Arab". Education According to CBS, 38 schools and 13,188 pupils are in the city. They are spread out as 26 elementary schools and 8,325 elementary school pupils, and 13 high schools and 4,863 high school pupils. About 52.5% of 12th-grade pupils were entitled to a matriculation certificate in 2001.[citation needed] Economy The airport and related industries are a major source of employment for the residents of Lod. Other important factories in the city are the communication equipment company "Talard", "Cafe-Co" - a subsidiary of the Strauss Group and "Kashev" - the computer center of Bank Leumi. A Jewish Agency Absorption Centre is also located in Lod. According to CBS figures for 2000, 23,032 people were salaried workers and 1,405 were self-employed. The mean monthly wage for a salaried worker was NIS 4,754, a real change of 2.9% over the course of 2000. Salaried men had a mean monthly wage of NIS 5,821 (a real change of 1.4%) versus NIS 3,547 for women (a real change of 4.6%). The mean income for the self-employed was NIS 4,991. About 1,275 people were receiving unemployment benefits and 7,145 were receiving an income supplement. Art and culture In 2009-2010, Dor Guez held an exhibit, Georgeopolis, at the Petach Tikva art museum that focuses on Lod. Archaeology A well-preserved mosaic floor dating to the Roman period was excavated in 1996 as part of a salvage dig conducted on behalf of the Israel Antiquities Authority and the Municipality of Lod, prior to widening HeHalutz Street. According to Jacob Fisch, executive director of the Friends of the Israel Antiquities Authority, a worker at the construction site noticed the tail of a tiger and halted work. The mosaic was initially covered over with soil at the conclusion of the excavation for lack of funds to conserve and develop the site. The mosaic is now part of the Lod Mosaic Archaeological Center. The floor, with its colorful display of birds, fish, exotic animals and merchant ships, is believed to have been commissioned by a wealthy resident of the city for his private home. The Lod Community Archaeology Program, which operates in ten Lod schools, five Jewish and five Israeli Arab, combines archaeological studies with participation in digs in Lod. Sports The city's major football club, Hapoel Bnei Lod, plays in Liga Leumit (the second division). Its home is at the Lod Municipal Stadium. The club was formed by a merger of Bnei Lod and Rakevet Lod in the 1980s. Two other clubs in the city play in the regional leagues: Hapoel MS Ortodoxim Lod in Liga Bet and Maccabi Lod in Liga Gimel. Hapoel Lod played in the top division during the 1960s and 1980s, and won the State Cup in 1984. The club folded in 2002. A new club, Hapoel Maxim Lod (named after former mayor Maxim Levy) was established soon after, but folded in 2007. Notable people Twin towns-sister cities Lod is twinned with: See also References Bibliography External links |
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[SOURCE: https://en.wikipedia.org/wiki/Transform_fault] | [TOKENS: 1891] |
Contents Transform fault A transform fault or transform boundary, is a fault along a plate boundary where the motion is predominantly horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subduction zone. A transform fault is a special case of a strike-slip fault that also forms a plate boundary. Most such faults are found in oceanic crust, where they accommodate the lateral offset between segments of divergent boundaries, forming a zigzag pattern. This results from oblique seafloor spreading where the direction of motion is not perpendicular to the trend of the overall divergent boundary. A smaller number of such faults are found on land, although these are generally better-known, such as the San Andreas Fault and North Anatolian Fault. Nomenclature Transform boundaries are also known as conservative plate boundaries because they involve no addition or loss of lithosphere at the Earth's surface. Background Geophysicist and geologist John Tuzo Wilson recognized that the offsets of oceanic ridges by faults do not follow the classical pattern of an offset fence or geological marker in Reid's rebound theory of faulting, from which the sense of slip is derived. The new class of faults, called transform faults, produce slip in the opposite direction from what one would surmise from the standard interpretation of an offset geological feature. Slip along transform faults does not increase the distance between the ridges it separates; the distance remains constant in earthquakes because the ridges are spreading centers. This hypothesis was confirmed in a study of the fault plane solutions that showed the slip on transform faults points in the opposite direction than classical interpretation would suggest. Difference between transform and transcurrent faults Transform faults are closely related to transcurrent faults and are commonly confused. Both types of fault are strike-slip or side-to-side in movement; nevertheless, transform faults always end at a junction with another plate boundary, while transcurrent faults may die out without a junction with another fault. Finally, transform faults form a tectonic plate boundary, while transcurrent faults do not. Mechanics Faults in general are focused areas of deformation or strain, which are the response of built-up stresses in the form of compression, tension, or shear stress in rock at the surface or deep in the Earth's subsurface. Transform faults specifically accommodate lateral strain by transferring displacement between mid-ocean ridges or subduction zones. They also act as the plane of weakness, which may result in splitting in rift zones.[citation needed] Transform faults and divergent boundaries Transform faults are commonly found linking segments of divergent boundaries (mid-oceanic ridges or spreading centres). These mid-oceanic ridges are where new seafloor is constantly created through the upwelling of new basaltic magma. With new seafloor being pushed and pulled out, the older seafloor slowly slides away from the mid-oceanic ridges toward the continents. Although separated only by tens of kilometers, this separation between segments of the ridges causes portions of the seafloor to push past each other in opposing directions. This lateral movement of seafloors past each other is where transform faults are currently active. Transform faults move differently from a strike-slip fault at the mid-oceanic ridge. Instead of the ridges moving away from each other, as they do in other strike-slip faults, transform-fault ridges remain in the same, fixed locations, and the new ocean seafloor created at the ridges is pushed away from the ridge. Evidence of this motion can be found in paleomagnetic striping on the seafloor. A paper written by geophysicist Taras Gerya theorizes that the creation of the transform faults between the ridges of the mid-oceanic ridge is attributed to rotated and stretched sections of the mid-oceanic ridge. This occurs over a long period of time with the spreading center or ridge slowly deforming from a straight line to a curved line. Finally, fracturing along these planes forms transform faults. As this takes place, the fault changes from a normal fault with extensional stress to a strike-slip fault with lateral stress. In the study done by Bonatti and Crane,[who?] peridotite and gabbro rocks were discovered in the edges of the transform ridges. These rocks are created deep inside the Earth's mantle and then rapidly exhumed to the surface. This evidence helps to prove that new seafloor is being created at the mid-oceanic ridges and further supports the theory of plate tectonics. Active transform faults are between two tectonic structures or faults. Fracture zones represent the previously active transform-fault lines, which have since passed the active transform zone and are being pushed toward the continents. These elevated ridges on the ocean floor can be traced for hundreds of miles and in some cases even from one continent across an ocean to the other continent. Types In his work on transform-fault systems, geologist Tuzo Wilson said that transform faults must be connected to other faults or tectonic-plate boundaries on both ends; because of that requirement, transform faults can grow in length, keep a constant length, or decrease in length. These length changes are dependent on which type of fault or tectonic structure connect with the transform fault. Wilson described six types of transform faults: Growing length: In situations where a transform fault links a spreading center and the upper block of a subduction zone or where two upper blocks of subduction zones are linked, the transform fault itself will grow in length. Constant length: In other cases, transform faults will remain at a constant length. This steadiness can be attributed to many different causes. In the case of ridge-to-ridge transforms, the constancy is caused by the continuous growth by both ridges outward, canceling any change in length. The opposite occurs when a ridge linked to a subducting plate, where all the lithosphere (new seafloor) being created by the ridge is subducted, or swallowed up, by the subduction zone. Finally, when two upper subduction plates are linked there is no change in length. This is due to the plates moving parallel with each other and no new lithosphere is being created to change that length. Decreasing length faults: In rare cases, transform faults can shrink in length. These occur when two descending subduction plates are linked by a transform fault. In time as the plates are subducted, the transform fault will decrease in length until the transform fault disappears completely, leaving only two subduction zones facing in opposite directions. Additionally, transform faults are chiral and can be classifed as sinistral and dextral based on orientation. When viewed from above, a sinistral fault has one block moving left with respect to the opposite block, while a dextral fault has one block moving right with respect to the opposite block. Examples The most prominent examples of the mid-oceanic ridge transform zones are in the Atlantic Ocean between South America and Africa. Known as the St. Paul, Romanche, Chain, and Ascension fracture zones, these areas have deep, easily identifiable transform faults and ridges. Other locations include: the East Pacific Ridge located in the South Eastern Pacific Ocean, which meets up with San Andreas Fault to the North. Transform faults are not limited to oceanic crust and spreading centers; many of them are on continental margins. The best example is the San Andreas Fault on the Pacific coast of the United States. The San Andreas Fault links the East Pacific Rise off the West coast of Mexico (Gulf of California) to the Mendocino triple junction (Part of the Juan de Fuca plate) off the coast of the Northwestern United States, making it a ridge-to-transform-style fault. The formation of the San Andreas Fault system occurred fairly recently during the Oligocene Period between 34 million and 24 million years ago. During this period, the Farallon plate, followed by the Pacific plate, collided into the North American plate. The collision led to the subduction of the Farallon plate underneath the North American plate. Once the spreading center separating the Pacific and the Farallon plates was subducted beneath the North American plate, the San Andreas Continental Transform-Fault system was created. In New Zealand, the South Island's Alpine Fault is a transform fault for much of its length. This has resulted in the folded land of the Southland Syncline being split into an eastern and western section several hundred kilometres apart. The majority of the syncline is found in Southland and The Catlins in the island's southeast, but a smaller section is also present in the Tasman District in the island's northwest. Another example is the Húsavík‐Flatey fault. This oceanic transform fault is nearly completely submerged, but ~10 km is exposed in northern Iceland, near the town of Húsavík. There, it manifests as a series of half-grabens and sharp fault scarps. Since oceanic transform faults are often difficult to research because of their submerged nature, this fault represents a rare opportunity for research. Scientists inspected Holocene earthquake activity by looking cross sections of the fault, and found the approximate earthquake frequency in the region to be 600 ± 200 years. Other examples include: See also References |
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[SOURCE: https://en.wikipedia.org/wiki/Plus_(programming_language)] | [TOKENS: 381] |
Contents Plus (programming language) Plus is a "Pascal-like" system implementation language from the University of British Columbia (UBC), Canada, based on the SUE system language developed at the University of Toronto, c. 1971.[a] Description Plus was developed at the University of British Columbia (UBC) Computing Centre by Alan Ballard and Paul Whaley for use with and for the development of the Michigan Terminal System (MTS), but the code generated by the compiler is not operating system dependent and so is not limited to use with or the development of MTS. The UBC Plus compiler is written largely in Plus, runs under the Michigan Terminal System (MTS) on IBM S/370 or compatible hardware or under IBM's OS/VS1, and generates code for the IBM S/370, the DEC PDP-11, or the Motorola 68000 architectures. Plus is based to a large extent on the SUE System Language developed at the University of Toronto, c. 1971, which in turn had been derived, particularly in its data structure facilities, from Pascal.[citation needed] Plus is superficially quite different from SUE or Pascal; however the underlying language semantics are really quite similar. Users familiar with the C programming language will also recognize much of its structure and semantics in PLUS. Goals for the compiler and the Plus language include: The compiler generates extensive source listings, including cross-references. In addition, it automatically formats the source using strict rules and has a simple mark-up language for comments. The manual, UBC PLUS: The Plus Programming Language, is available. A description of the source and object libraries available for use with Plus, PLUS Source Library Definitions, is also available. "Hello, world" example The "hello, world" example program prints the string "Hello, world!" to a terminal or screen display. See also Notes References |
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[SOURCE: https://en.wikipedia.org/wiki/Orion_(constellation)#cite_ref-15] | [TOKENS: 4993] |
Contents Orion (constellation) Orion is a prominent set of stars visible during winter in the northern celestial hemisphere. It is one of the 88 modern constellations; it was among the 48 constellations listed by the 2nd-century AD/CE astronomer Ptolemy. It is named after a hunter in Greek mythology. Orion is most prominent during winter evenings in the Northern Hemisphere, as are five other constellations that have stars in the Winter Hexagon asterism. Orion's two brightest stars, Rigel (β) and Betelgeuse (α), are both among the brightest stars in the night sky; both are supergiants and slightly variable. There are a further six stars brighter than magnitude 3.0, including three making the short straight line of the Orion's Belt asterism. Orion also hosts the radiant of the annual Orionids, the strongest meteor shower associated with Halley's Comet, and the Orion Nebula, one of the brightest nebulae in the sky. Characteristics Orion is bordered by Taurus to the northwest, Eridanus to the southwest, Lepus to the south, Monoceros to the east, and Gemini to the northeast. Covering 594 square degrees, Orion ranks 26th of the 88 constellations in size. The constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of 26 sides. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 04h 43.3m and 06h 25.5m , while the declination coordinates are between 22.87° and −10.97°. The constellation's three-letter abbreviation, as adopted by the International Astronomical Union in 1922, is "Ori". Orion is most visible in the evening sky from January to April, winter in the Northern Hemisphere, and summer in the Southern Hemisphere. In the tropics (less than about 8° from the equator), the constellation transits at the zenith. From May to July (summer in the Northern Hemisphere, winter in the Southern Hemisphere), Orion is in the daytime sky and thus invisible at most latitudes. However, for much of Antarctica in the Southern Hemisphere's winter months, the Sun is below the horizon even at midday. Stars (and thus Orion, but only the brightest stars) are then visible at twilight for a few hours around local noon, just in the brightest section of the sky low in the North where the Sun is just below the horizon. At the same time of day at the South Pole itself (Amundsen–Scott South Pole Station), Rigel is only 8° above the horizon, and the Belt sweeps just along it. In the Southern Hemisphere's summer months, when Orion is normally visible in the night sky, the constellation is actually not visible in Antarctica because the Sun does not set at that time of year south of the Antarctic Circle. In countries close to the equator (e.g. Kenya, Indonesia, Colombia, Ecuador), Orion appears overhead in December around midnight and in the February evening sky. Navigational aid Orion is very useful as an aid to locating other stars. By extending the line of the Belt southeastward, Sirius (α CMa) can be found; northwestward, Aldebaran (α Tau). A line eastward across the two shoulders indicates the direction of Procyon (α CMi). A line from Rigel through Betelgeuse points to Castor and Pollux (α Gem and β Gem). Additionally, Rigel is part of the Winter Circle asterism. Sirius and Procyon, which may be located from Orion by following imaginary lines (see map), also are points in both the Winter Triangle and the Circle. Features Orion's seven brightest stars form a distinctive hourglass-shaped asterism, or pattern, in the night sky. Four stars—Rigel, Betelgeuse, Bellatrix, and Saiph—form a large roughly rectangular shape, at the center of which lie the three stars of Orion's Belt—Alnitak, Alnilam, and Mintaka. His head is marked by an additional eighth star called Meissa, which is fairly bright to the observer. Descending from the Belt is a smaller line of three stars, Orion's Sword (the middle of which is in fact not a star but the Orion Nebula), also known as the hunter's sword. Many of the stars are luminous hot blue supergiants, with the stars of the Belt and Sword forming the Orion OB1 association. Standing out by its red hue, Betelgeuse may nevertheless be a runaway member of the same group. Orion's Belt, or The Belt of Orion, is an asterism within the constellation. It consists of three bright stars: Alnitak (Zeta Orionis), Alnilam (Epsilon Orionis), and Mintaka (Delta Orionis). Alnitak is around 800 light-years away from Earth, 100,000 times more luminous than the Sun, and shines with a magnitude of 1.8; much of its radiation is in the ultraviolet range, which the human eye cannot see. Alnilam is approximately 2,000 light-years from Earth, shines with a magnitude of 1.70, and with an ultraviolet light that is 375,000 times more luminous than the Sun. Mintaka is 915 light-years away and shines with a magnitude of 2.21. It is 90,000 times more luminous than the Sun and is a double star: the two orbit each other every 5.73 days. In the Northern Hemisphere, Orion's Belt is best visible in the night sky during the month of January at around 9:00 pm, when it is approximately around the local meridian. Just southwest of Alnitak lies Sigma Orionis, a multiple star system composed of five stars that have a combined apparent magnitude of 3.7 and lying at a distance of 1150 light-years. Southwest of Mintaka lies the quadruple star Eta Orionis. Orion's Sword contains the Orion Nebula, the Messier 43 nebula, Sh 2-279 (also known as the Running Man Nebula), and the stars Theta Orionis, Iota Orionis, and 42 Orionis. Three stars comprise a small triangle that marks the head. The apex is marked by Meissa (Lambda Orionis), a hot blue giant of spectral type O8 III and apparent magnitude 3.54, which lies some 1100 light-years distant. Phi-1 and Phi-2 Orionis make up the base. Also nearby is the young star FU Orionis. Stretching north from Betelgeuse are the stars that make up Orion's club. Mu Orionis marks the elbow, Nu and Xi mark the handle of the club, and Chi1 and Chi2 mark the end of the club. Just east of Chi1 is the Mira-type variable red giant star U Orionis. West from Bellatrix lie six stars all designated Pi Orionis (π1 Ori, π2 Ori, π3 Ori, π4 Ori, π5 Ori, and π6 Ori) which make up Orion's shield. Around 20 October each year, the Orionid meteor shower (Orionids) reaches its peak. Coming from the border with the constellation Gemini, as many as 20 meteors per hour can be seen. The shower's parent body is Halley's Comet. Hanging from Orion's Belt is his sword, consisting of the multiple stars θ1 and θ2 Orionis, called the Trapezium and the Orion Nebula (M42). This is a spectacular object that can be clearly identified with the naked eye as something other than a star. Using binoculars, its clouds of nascent stars, luminous gas, and dust can be observed. The Trapezium cluster has many newborn stars, including several brown dwarfs, all of which are at an approximate distance of 1,500 light-years. Named for the four bright stars that form a trapezoid, it is largely illuminated by the brightest stars, which are only a few hundred thousand years old. Observations by the Chandra X-ray Observatory show both the extreme temperatures of the main stars—up to 60,000 kelvins—and the star forming regions still extant in the surrounding nebula. M78 (NGC 2068) is a nebula in Orion. With an overall magnitude of 8.0, it is significantly dimmer than the Great Orion Nebula that lies to its south; however, it is at approximately the same distance, at 1600 light-years from Earth. It can easily be mistaken for a comet in the eyepiece of a telescope. M78 is associated with the variable star V351 Orionis, whose magnitude changes are visible in very short periods of time. Another fairly bright nebula in Orion is NGC 1999, also close to the Great Orion Nebula. It has an integrated magnitude of 10.5 and is 1500 light-years from Earth. The variable star V380 Orionis is embedded in NGC 1999. Another famous nebula is IC 434, the Horsehead Nebula, near Alnitak (Zeta Orionis). It contains a dark dust cloud whose shape gives the nebula its name. NGC 2174 is an emission nebula located 6400 light-years from Earth. Besides these nebulae, surveying Orion with a small telescope will reveal a wealth of interesting deep-sky objects, including M43, M78, and multiple stars including Iota Orionis and Sigma Orionis. A larger telescope may reveal objects such as the Flame Nebula (NGC 2024), as well as fainter and tighter multiple stars and nebulae. Barnard's Loop can be seen on very dark nights or using long-exposure photography. All of these nebulae are part of the larger Orion molecular cloud complex, which is located approximately 1,500 light-years away and is hundreds of light-years across. Due to its proximity, it is one of the most intense regions of stellar formation visible from Earth. The Orion molecular cloud complex forms the eastern part of an even larger structure, the Orion–Eridanus Superbubble, which is visible in X-rays and in hydrogen emissions. History and mythology The distinctive pattern of Orion is recognized in numerous cultures around the world, and many myths are associated with it. Orion is used as a symbol in the modern world. In Siberia, the Chukchi people see Orion as a hunter; an arrow he has shot is represented by Aldebaran (Alpha Tauri), with the same figure as other Western depictions. In Greek mythology, Orion was a gigantic, supernaturally strong hunter, born to Euryale, a Gorgon, and Poseidon (Neptune), god of the sea. One myth recounts Gaia's rage at Orion, who dared to say that he would kill every animal on Earth. The angry goddess tried to dispatch Orion with a scorpion. This is given as the reason that the constellations of Scorpius and Orion are never in the sky at the same time. However, Ophiuchus, the Serpent Bearer, revived Orion with an antidote. This is said to be the reason that the constellation of Ophiuchus stands midway between the Scorpion and the Hunter in the sky. The constellation is mentioned in Horace's Odes (Ode 3.27.18), Homer's Odyssey (Book 5, line 283) and Iliad, and Virgil's Aeneid (Book 1, line 535). In old Hungarian tradition, Orion is known as "Archer" (Íjász), or "Reaper" (Kaszás). In recently rediscovered myths, he is called Nimrod (Hungarian: Nimród), the greatest hunter, father of the twins Hunor and Magor. The π and o stars (on upper right) form together the reflex bow or the lifted scythe. In other Hungarian traditions, Orion's Belt is known as "Judge's stick" (Bírópálca). In Ireland and Scotland, Orion was called An Bodach, a figure from Irish folklore whose name literally means "the one with a penis [bod]" and was the husband of the Cailleach (hag). In Scandinavian tradition, Orion's Belt was known as "Frigg's Distaff" (friggerock) or "Freyja's distaff". The Finns call Orion's Belt and the stars below it "Väinämöinen's scythe" (Väinämöisen viikate). Another name for the asterism of Alnilam, Alnitak, and Mintaka is "Väinämöinen's Belt" (Väinämöisen vyö) and the stars "hanging" from the Belt as "Kaleva's sword" (Kalevanmiekka). There are claims in popular media that the Adorant from the Geißenklösterle cave, an ivory carving estimated to be 35,000 to 40,000 years old, is the first known depiction of the constellation. Scholars dismiss such interpretations, saying that perceived details such as a belt and sword derive from preexisting features in the grain structure of the ivory. The Babylonian star catalogues of the Late Bronze Age name Orion MULSIPA.ZI.AN.NA,[note 1] "The Heavenly Shepherd" or "True Shepherd of Anu" – Anu being the chief god of the heavenly realms. The Babylonian constellation is sacred to Papshukal and Ninshubur, both minor gods fulfilling the role of "messenger to the gods". Papshukal is closely associated with the figure of a walking bird on Babylonian boundary stones, and on the star map the figure of the Rooster is located below and behind the figure of the True Shepherd—both constellations represent the herald of the gods, in his bird and human forms respectively. In ancient Egypt, the stars of Orion were regarded as a god, called Sah. Because Orion rises before Sirius, the star whose heliacal rising was the basis for the Solar Egyptian calendar, Sah was closely linked with Sopdet, the goddess who personified Sirius. The god Sopdu is said to be the son of Sah and Sopdet. Sah is syncretized with Osiris, while Sopdet is syncretized with Osiris' mythological wife, Isis. In the Pyramid Texts, from the 24th and 23rd centuries BC, Sah is one of many gods whose form the dead pharaoh is said to take in the afterlife. The Armenians identified their legendary patriarch and founder Hayk with Orion. Hayk is also the name of the Orion constellation in the Armenian translation of the Bible. The Bible mentions Orion three times, naming it "Kesil" (כסיל, literally – fool). Though, this name perhaps is etymologically connected with "Kislev", the name for the ninth month of the Hebrew calendar (i.e. November–December), which, in turn, may derive from the Hebrew root K-S-L as in the words "kesel, kisla" (כֵּסֶל, כִּסְלָה, hope, positiveness), i.e. hope for winter rains.: Job 9:9 ("He is the maker of the Bear and Orion"), Job 38:31 ("Can you loosen Orion's belt?"), and Amos 5:8 ("He who made the Pleiades and Orion"). In ancient Aram, the constellation was known as Nephîlā′, the Nephilim are said to be Orion's descendants. In medieval Muslim astronomy, Orion was known as al-jabbar, "the giant". Orion's sixth brightest star, Saiph, is named from the Arabic, saif al-jabbar, meaning "sword of the giant". In China, Orion was one of the 28 lunar mansions Sieu (Xiù) (宿). It is known as Shen (參), literally meaning "three", for the stars of Orion's Belt. The Chinese character 參 (pinyin shēn) originally meant the constellation Orion (Chinese: 參宿; pinyin: shēnxiù); its Shang dynasty version, over three millennia old, contains at the top a representation of the three stars of Orion's Belt atop a man's head (the bottom portion representing the sound of the word was added later). The Rigveda refers to the constellation as Mriga (the Deer). Nataraja, "the cosmic dancer", is often interpreted as the representation of Orion. Rudra, the Rigvedic form of Shiva, is the presiding deity of Ardra nakshatra (Betelgeuse) of Hindu astrology. The Jain Symbol carved in the Udayagiri and Khandagiri Caves, India in 1st century BCE has a striking resemblance with Orion. Bugis sailors identified the three stars in Orion's Belt as tanra tellué, meaning "sign of three". The Seri people of northwestern Mexico call the three stars in Orion's Belt Hapj (a name denoting a hunter) which consists of three stars: Hap (mule deer), Haamoja (pronghorn), and Mojet (bighorn sheep). Hap is in the middle and has been shot by the hunter; its blood has dripped onto Tiburón Island. The same three stars are known in Spain and most of Latin America as "Las tres Marías" (Spanish for "The Three Marys"). In Puerto Rico, the three stars are known as the "Los Tres Reyes Magos" (Spanish for The Three Wise Men). The Ojibwa/Chippewa Native Americans call this constellation Mesabi for Big Man. To the Lakota Native Americans, Tayamnicankhu (Orion's Belt) is the spine of a bison. The great rectangle of Orion is the bison's ribs; the Pleiades star cluster in nearby Taurus is the bison's head; and Sirius in Canis Major, known as Tayamnisinte, is its tail. Another Lakota myth mentions that the bottom half of Orion, the Constellation of the Hand, represented the arm of a chief that was ripped off by the Thunder People as a punishment from the gods for his selfishness. His daughter offered to marry the person who can retrieve his arm from the sky, so the young warrior Fallen Star (whose father was a star and whose mother was human) returned his arm and married his daughter, symbolizing harmony between the gods and humanity with the help of the younger generation. The index finger is represented by Rigel; the Orion Nebula is the thumb; the Belt of Orion is the wrist; and the star Beta Eridani is the pinky finger. The seven primary stars of Orion make up the Polynesian constellation Heiheionakeiki which represents a child's string figure similar to a cat's cradle. Several precolonial Filipinos referred to the belt region in particular as "balatik" (ballista) as it resembles a trap of the same name which fires arrows by itself and is usually used for catching pigs from the bush. Spanish colonization later led to some ethnic groups referring to Orion's Belt as "Tres Marias" or "Tatlong Maria." In Māori tradition, the star Rigel (known as Puanga or Puaka) is closely connected with the celebration of Matariki. The rising of Matariki (the Pleiades) and Rigel before sunrise in midwinter marks the start of the Māori year. In Javanese culture, the constellation is often called Lintang Waluku or Bintang Bajak, referring to the shape of a paddy field plow. The imagery of the Belt and Sword has found its way into popular Western culture, for example in the form of the shoulder insignia of the 27th Infantry Division of the United States Army during both World Wars, probably owing to a pun on the name of the division's first commander, Major General John F. O'Ryan. The film distribution company Orion Pictures used the constellation as its logo. In artistic renderings, the surrounding constellations are sometimes related to Orion: he is depicted standing next to the river Eridanus with his two hunting dogs Canis Major and Canis Minor, fighting Taurus. He is sometimes depicted hunting Lepus the hare. He sometimes is depicted to have a lion's hide in his hand. There are alternative ways to visualise Orion. From the Southern Hemisphere, Orion is oriented south-upward, and the Belt and Sword are sometimes called the saucepan or pot in Australia and New Zealand. Orion's Belt is called Drie Konings (Three Kings) or the Drie Susters (Three Sisters) by Afrikaans speakers in South Africa and are referred to as les Trois Rois (the Three Kings) in Daudet's Lettres de Mon Moulin (1866). The appellation Driekoningen (the Three Kings) is also often found in 17th and 18th-century Dutch star charts and seaman's guides. The same three stars are known in Spain, Latin America, and the Philippines as "Las Tres Marías" (The Three Marys), and as "Los Tres Reyes Magos" (The Three Wise Men) in Puerto Rico. Even traditional depictions of Orion have varied greatly. Cicero drew Orion in a similar fashion to the modern depiction. The Hunter held an unidentified animal skin aloft in his right hand; his hand was represented by Omicron2 Orionis and the skin was represented by the five stars designated Pi Orionis. Saiph and Rigel represented his left and right knees, while Eta Orionis and Lambda Leporis were his left and right feet, respectively. As in the modern depiction, Mintaka, Alnilam, and Alnitak represented his Belt. His left shoulder was represented by Betelgeuse, and Mu Orionis made up his left arm. Meissa was his head, and Bellatrix his right shoulder. The depiction of Hyginus was similar to that of Cicero, though the two differed in a few important areas. Cicero's animal skin became Hyginus's shield (Omicron and Pi Orionis), and instead of an arm marked out by Mu Orionis, he holds a club (Chi Orionis). His right leg is represented by Theta Orionis and his left leg is represented by Lambda, Mu, and Epsilon Leporis. Further Western European and Arabic depictions have followed these two models. Future Orion is located on the celestial equator, but it will not always be so located due to the effects of precession of the Earth's axis. Orion lies well south of the ecliptic, and it only happens to lie on the celestial equator because the point on the ecliptic that corresponds to the June solstice is close to the border of Gemini and Taurus, to the north of Orion. Precession will eventually carry Orion further south, and by AD 14000, Orion will be far enough south that it will no longer be visible from the latitude of Great Britain. Further in the future, Orion's stars will gradually move away from the constellation due to proper motion. However, Orion's brightest stars all lie at a large distance from Earth on an astronomical scale—much farther away than Sirius, for example. Orion will still be recognizable long after most of the other constellations—composed of relatively nearby stars—have distorted into new configurations, with the exception of a few of its stars eventually exploding as supernovae, for example Betelgeuse, which is predicted to explode sometime in the next million years. See also References External links |
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[SOURCE: https://en.wikipedia.org/wiki/Orion_(constellation)#cite_ref-UIUCBELLA_13-0] | [TOKENS: 4993] |
Contents Orion (constellation) Orion is a prominent set of stars visible during winter in the northern celestial hemisphere. It is one of the 88 modern constellations; it was among the 48 constellations listed by the 2nd-century AD/CE astronomer Ptolemy. It is named after a hunter in Greek mythology. Orion is most prominent during winter evenings in the Northern Hemisphere, as are five other constellations that have stars in the Winter Hexagon asterism. Orion's two brightest stars, Rigel (β) and Betelgeuse (α), are both among the brightest stars in the night sky; both are supergiants and slightly variable. There are a further six stars brighter than magnitude 3.0, including three making the short straight line of the Orion's Belt asterism. Orion also hosts the radiant of the annual Orionids, the strongest meteor shower associated with Halley's Comet, and the Orion Nebula, one of the brightest nebulae in the sky. Characteristics Orion is bordered by Taurus to the northwest, Eridanus to the southwest, Lepus to the south, Monoceros to the east, and Gemini to the northeast. Covering 594 square degrees, Orion ranks 26th of the 88 constellations in size. The constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of 26 sides. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 04h 43.3m and 06h 25.5m , while the declination coordinates are between 22.87° and −10.97°. The constellation's three-letter abbreviation, as adopted by the International Astronomical Union in 1922, is "Ori". Orion is most visible in the evening sky from January to April, winter in the Northern Hemisphere, and summer in the Southern Hemisphere. In the tropics (less than about 8° from the equator), the constellation transits at the zenith. From May to July (summer in the Northern Hemisphere, winter in the Southern Hemisphere), Orion is in the daytime sky and thus invisible at most latitudes. However, for much of Antarctica in the Southern Hemisphere's winter months, the Sun is below the horizon even at midday. Stars (and thus Orion, but only the brightest stars) are then visible at twilight for a few hours around local noon, just in the brightest section of the sky low in the North where the Sun is just below the horizon. At the same time of day at the South Pole itself (Amundsen–Scott South Pole Station), Rigel is only 8° above the horizon, and the Belt sweeps just along it. In the Southern Hemisphere's summer months, when Orion is normally visible in the night sky, the constellation is actually not visible in Antarctica because the Sun does not set at that time of year south of the Antarctic Circle. In countries close to the equator (e.g. Kenya, Indonesia, Colombia, Ecuador), Orion appears overhead in December around midnight and in the February evening sky. Navigational aid Orion is very useful as an aid to locating other stars. By extending the line of the Belt southeastward, Sirius (α CMa) can be found; northwestward, Aldebaran (α Tau). A line eastward across the two shoulders indicates the direction of Procyon (α CMi). A line from Rigel through Betelgeuse points to Castor and Pollux (α Gem and β Gem). Additionally, Rigel is part of the Winter Circle asterism. Sirius and Procyon, which may be located from Orion by following imaginary lines (see map), also are points in both the Winter Triangle and the Circle. Features Orion's seven brightest stars form a distinctive hourglass-shaped asterism, or pattern, in the night sky. Four stars—Rigel, Betelgeuse, Bellatrix, and Saiph—form a large roughly rectangular shape, at the center of which lie the three stars of Orion's Belt—Alnitak, Alnilam, and Mintaka. His head is marked by an additional eighth star called Meissa, which is fairly bright to the observer. Descending from the Belt is a smaller line of three stars, Orion's Sword (the middle of which is in fact not a star but the Orion Nebula), also known as the hunter's sword. Many of the stars are luminous hot blue supergiants, with the stars of the Belt and Sword forming the Orion OB1 association. Standing out by its red hue, Betelgeuse may nevertheless be a runaway member of the same group. Orion's Belt, or The Belt of Orion, is an asterism within the constellation. It consists of three bright stars: Alnitak (Zeta Orionis), Alnilam (Epsilon Orionis), and Mintaka (Delta Orionis). Alnitak is around 800 light-years away from Earth, 100,000 times more luminous than the Sun, and shines with a magnitude of 1.8; much of its radiation is in the ultraviolet range, which the human eye cannot see. Alnilam is approximately 2,000 light-years from Earth, shines with a magnitude of 1.70, and with an ultraviolet light that is 375,000 times more luminous than the Sun. Mintaka is 915 light-years away and shines with a magnitude of 2.21. It is 90,000 times more luminous than the Sun and is a double star: the two orbit each other every 5.73 days. In the Northern Hemisphere, Orion's Belt is best visible in the night sky during the month of January at around 9:00 pm, when it is approximately around the local meridian. Just southwest of Alnitak lies Sigma Orionis, a multiple star system composed of five stars that have a combined apparent magnitude of 3.7 and lying at a distance of 1150 light-years. Southwest of Mintaka lies the quadruple star Eta Orionis. Orion's Sword contains the Orion Nebula, the Messier 43 nebula, Sh 2-279 (also known as the Running Man Nebula), and the stars Theta Orionis, Iota Orionis, and 42 Orionis. Three stars comprise a small triangle that marks the head. The apex is marked by Meissa (Lambda Orionis), a hot blue giant of spectral type O8 III and apparent magnitude 3.54, which lies some 1100 light-years distant. Phi-1 and Phi-2 Orionis make up the base. Also nearby is the young star FU Orionis. Stretching north from Betelgeuse are the stars that make up Orion's club. Mu Orionis marks the elbow, Nu and Xi mark the handle of the club, and Chi1 and Chi2 mark the end of the club. Just east of Chi1 is the Mira-type variable red giant star U Orionis. West from Bellatrix lie six stars all designated Pi Orionis (π1 Ori, π2 Ori, π3 Ori, π4 Ori, π5 Ori, and π6 Ori) which make up Orion's shield. Around 20 October each year, the Orionid meteor shower (Orionids) reaches its peak. Coming from the border with the constellation Gemini, as many as 20 meteors per hour can be seen. The shower's parent body is Halley's Comet. Hanging from Orion's Belt is his sword, consisting of the multiple stars θ1 and θ2 Orionis, called the Trapezium and the Orion Nebula (M42). This is a spectacular object that can be clearly identified with the naked eye as something other than a star. Using binoculars, its clouds of nascent stars, luminous gas, and dust can be observed. The Trapezium cluster has many newborn stars, including several brown dwarfs, all of which are at an approximate distance of 1,500 light-years. Named for the four bright stars that form a trapezoid, it is largely illuminated by the brightest stars, which are only a few hundred thousand years old. Observations by the Chandra X-ray Observatory show both the extreme temperatures of the main stars—up to 60,000 kelvins—and the star forming regions still extant in the surrounding nebula. M78 (NGC 2068) is a nebula in Orion. With an overall magnitude of 8.0, it is significantly dimmer than the Great Orion Nebula that lies to its south; however, it is at approximately the same distance, at 1600 light-years from Earth. It can easily be mistaken for a comet in the eyepiece of a telescope. M78 is associated with the variable star V351 Orionis, whose magnitude changes are visible in very short periods of time. Another fairly bright nebula in Orion is NGC 1999, also close to the Great Orion Nebula. It has an integrated magnitude of 10.5 and is 1500 light-years from Earth. The variable star V380 Orionis is embedded in NGC 1999. Another famous nebula is IC 434, the Horsehead Nebula, near Alnitak (Zeta Orionis). It contains a dark dust cloud whose shape gives the nebula its name. NGC 2174 is an emission nebula located 6400 light-years from Earth. Besides these nebulae, surveying Orion with a small telescope will reveal a wealth of interesting deep-sky objects, including M43, M78, and multiple stars including Iota Orionis and Sigma Orionis. A larger telescope may reveal objects such as the Flame Nebula (NGC 2024), as well as fainter and tighter multiple stars and nebulae. Barnard's Loop can be seen on very dark nights or using long-exposure photography. All of these nebulae are part of the larger Orion molecular cloud complex, which is located approximately 1,500 light-years away and is hundreds of light-years across. Due to its proximity, it is one of the most intense regions of stellar formation visible from Earth. The Orion molecular cloud complex forms the eastern part of an even larger structure, the Orion–Eridanus Superbubble, which is visible in X-rays and in hydrogen emissions. History and mythology The distinctive pattern of Orion is recognized in numerous cultures around the world, and many myths are associated with it. Orion is used as a symbol in the modern world. In Siberia, the Chukchi people see Orion as a hunter; an arrow he has shot is represented by Aldebaran (Alpha Tauri), with the same figure as other Western depictions. In Greek mythology, Orion was a gigantic, supernaturally strong hunter, born to Euryale, a Gorgon, and Poseidon (Neptune), god of the sea. One myth recounts Gaia's rage at Orion, who dared to say that he would kill every animal on Earth. The angry goddess tried to dispatch Orion with a scorpion. This is given as the reason that the constellations of Scorpius and Orion are never in the sky at the same time. However, Ophiuchus, the Serpent Bearer, revived Orion with an antidote. This is said to be the reason that the constellation of Ophiuchus stands midway between the Scorpion and the Hunter in the sky. The constellation is mentioned in Horace's Odes (Ode 3.27.18), Homer's Odyssey (Book 5, line 283) and Iliad, and Virgil's Aeneid (Book 1, line 535). In old Hungarian tradition, Orion is known as "Archer" (Íjász), or "Reaper" (Kaszás). In recently rediscovered myths, he is called Nimrod (Hungarian: Nimród), the greatest hunter, father of the twins Hunor and Magor. The π and o stars (on upper right) form together the reflex bow or the lifted scythe. In other Hungarian traditions, Orion's Belt is known as "Judge's stick" (Bírópálca). In Ireland and Scotland, Orion was called An Bodach, a figure from Irish folklore whose name literally means "the one with a penis [bod]" and was the husband of the Cailleach (hag). In Scandinavian tradition, Orion's Belt was known as "Frigg's Distaff" (friggerock) or "Freyja's distaff". The Finns call Orion's Belt and the stars below it "Väinämöinen's scythe" (Väinämöisen viikate). Another name for the asterism of Alnilam, Alnitak, and Mintaka is "Väinämöinen's Belt" (Väinämöisen vyö) and the stars "hanging" from the Belt as "Kaleva's sword" (Kalevanmiekka). There are claims in popular media that the Adorant from the Geißenklösterle cave, an ivory carving estimated to be 35,000 to 40,000 years old, is the first known depiction of the constellation. Scholars dismiss such interpretations, saying that perceived details such as a belt and sword derive from preexisting features in the grain structure of the ivory. The Babylonian star catalogues of the Late Bronze Age name Orion MULSIPA.ZI.AN.NA,[note 1] "The Heavenly Shepherd" or "True Shepherd of Anu" – Anu being the chief god of the heavenly realms. The Babylonian constellation is sacred to Papshukal and Ninshubur, both minor gods fulfilling the role of "messenger to the gods". Papshukal is closely associated with the figure of a walking bird on Babylonian boundary stones, and on the star map the figure of the Rooster is located below and behind the figure of the True Shepherd—both constellations represent the herald of the gods, in his bird and human forms respectively. In ancient Egypt, the stars of Orion were regarded as a god, called Sah. Because Orion rises before Sirius, the star whose heliacal rising was the basis for the Solar Egyptian calendar, Sah was closely linked with Sopdet, the goddess who personified Sirius. The god Sopdu is said to be the son of Sah and Sopdet. Sah is syncretized with Osiris, while Sopdet is syncretized with Osiris' mythological wife, Isis. In the Pyramid Texts, from the 24th and 23rd centuries BC, Sah is one of many gods whose form the dead pharaoh is said to take in the afterlife. The Armenians identified their legendary patriarch and founder Hayk with Orion. Hayk is also the name of the Orion constellation in the Armenian translation of the Bible. The Bible mentions Orion three times, naming it "Kesil" (כסיל, literally – fool). Though, this name perhaps is etymologically connected with "Kislev", the name for the ninth month of the Hebrew calendar (i.e. November–December), which, in turn, may derive from the Hebrew root K-S-L as in the words "kesel, kisla" (כֵּסֶל, כִּסְלָה, hope, positiveness), i.e. hope for winter rains.: Job 9:9 ("He is the maker of the Bear and Orion"), Job 38:31 ("Can you loosen Orion's belt?"), and Amos 5:8 ("He who made the Pleiades and Orion"). In ancient Aram, the constellation was known as Nephîlā′, the Nephilim are said to be Orion's descendants. In medieval Muslim astronomy, Orion was known as al-jabbar, "the giant". Orion's sixth brightest star, Saiph, is named from the Arabic, saif al-jabbar, meaning "sword of the giant". In China, Orion was one of the 28 lunar mansions Sieu (Xiù) (宿). It is known as Shen (參), literally meaning "three", for the stars of Orion's Belt. The Chinese character 參 (pinyin shēn) originally meant the constellation Orion (Chinese: 參宿; pinyin: shēnxiù); its Shang dynasty version, over three millennia old, contains at the top a representation of the three stars of Orion's Belt atop a man's head (the bottom portion representing the sound of the word was added later). The Rigveda refers to the constellation as Mriga (the Deer). Nataraja, "the cosmic dancer", is often interpreted as the representation of Orion. Rudra, the Rigvedic form of Shiva, is the presiding deity of Ardra nakshatra (Betelgeuse) of Hindu astrology. The Jain Symbol carved in the Udayagiri and Khandagiri Caves, India in 1st century BCE has a striking resemblance with Orion. Bugis sailors identified the three stars in Orion's Belt as tanra tellué, meaning "sign of three". The Seri people of northwestern Mexico call the three stars in Orion's Belt Hapj (a name denoting a hunter) which consists of three stars: Hap (mule deer), Haamoja (pronghorn), and Mojet (bighorn sheep). Hap is in the middle and has been shot by the hunter; its blood has dripped onto Tiburón Island. The same three stars are known in Spain and most of Latin America as "Las tres Marías" (Spanish for "The Three Marys"). In Puerto Rico, the three stars are known as the "Los Tres Reyes Magos" (Spanish for The Three Wise Men). The Ojibwa/Chippewa Native Americans call this constellation Mesabi for Big Man. To the Lakota Native Americans, Tayamnicankhu (Orion's Belt) is the spine of a bison. The great rectangle of Orion is the bison's ribs; the Pleiades star cluster in nearby Taurus is the bison's head; and Sirius in Canis Major, known as Tayamnisinte, is its tail. Another Lakota myth mentions that the bottom half of Orion, the Constellation of the Hand, represented the arm of a chief that was ripped off by the Thunder People as a punishment from the gods for his selfishness. His daughter offered to marry the person who can retrieve his arm from the sky, so the young warrior Fallen Star (whose father was a star and whose mother was human) returned his arm and married his daughter, symbolizing harmony between the gods and humanity with the help of the younger generation. The index finger is represented by Rigel; the Orion Nebula is the thumb; the Belt of Orion is the wrist; and the star Beta Eridani is the pinky finger. The seven primary stars of Orion make up the Polynesian constellation Heiheionakeiki which represents a child's string figure similar to a cat's cradle. Several precolonial Filipinos referred to the belt region in particular as "balatik" (ballista) as it resembles a trap of the same name which fires arrows by itself and is usually used for catching pigs from the bush. Spanish colonization later led to some ethnic groups referring to Orion's Belt as "Tres Marias" or "Tatlong Maria." In Māori tradition, the star Rigel (known as Puanga or Puaka) is closely connected with the celebration of Matariki. The rising of Matariki (the Pleiades) and Rigel before sunrise in midwinter marks the start of the Māori year. In Javanese culture, the constellation is often called Lintang Waluku or Bintang Bajak, referring to the shape of a paddy field plow. The imagery of the Belt and Sword has found its way into popular Western culture, for example in the form of the shoulder insignia of the 27th Infantry Division of the United States Army during both World Wars, probably owing to a pun on the name of the division's first commander, Major General John F. O'Ryan. The film distribution company Orion Pictures used the constellation as its logo. In artistic renderings, the surrounding constellations are sometimes related to Orion: he is depicted standing next to the river Eridanus with his two hunting dogs Canis Major and Canis Minor, fighting Taurus. He is sometimes depicted hunting Lepus the hare. He sometimes is depicted to have a lion's hide in his hand. There are alternative ways to visualise Orion. From the Southern Hemisphere, Orion is oriented south-upward, and the Belt and Sword are sometimes called the saucepan or pot in Australia and New Zealand. Orion's Belt is called Drie Konings (Three Kings) or the Drie Susters (Three Sisters) by Afrikaans speakers in South Africa and are referred to as les Trois Rois (the Three Kings) in Daudet's Lettres de Mon Moulin (1866). The appellation Driekoningen (the Three Kings) is also often found in 17th and 18th-century Dutch star charts and seaman's guides. The same three stars are known in Spain, Latin America, and the Philippines as "Las Tres Marías" (The Three Marys), and as "Los Tres Reyes Magos" (The Three Wise Men) in Puerto Rico. Even traditional depictions of Orion have varied greatly. Cicero drew Orion in a similar fashion to the modern depiction. The Hunter held an unidentified animal skin aloft in his right hand; his hand was represented by Omicron2 Orionis and the skin was represented by the five stars designated Pi Orionis. Saiph and Rigel represented his left and right knees, while Eta Orionis and Lambda Leporis were his left and right feet, respectively. As in the modern depiction, Mintaka, Alnilam, and Alnitak represented his Belt. His left shoulder was represented by Betelgeuse, and Mu Orionis made up his left arm. Meissa was his head, and Bellatrix his right shoulder. The depiction of Hyginus was similar to that of Cicero, though the two differed in a few important areas. Cicero's animal skin became Hyginus's shield (Omicron and Pi Orionis), and instead of an arm marked out by Mu Orionis, he holds a club (Chi Orionis). His right leg is represented by Theta Orionis and his left leg is represented by Lambda, Mu, and Epsilon Leporis. Further Western European and Arabic depictions have followed these two models. Future Orion is located on the celestial equator, but it will not always be so located due to the effects of precession of the Earth's axis. Orion lies well south of the ecliptic, and it only happens to lie on the celestial equator because the point on the ecliptic that corresponds to the June solstice is close to the border of Gemini and Taurus, to the north of Orion. Precession will eventually carry Orion further south, and by AD 14000, Orion will be far enough south that it will no longer be visible from the latitude of Great Britain. Further in the future, Orion's stars will gradually move away from the constellation due to proper motion. However, Orion's brightest stars all lie at a large distance from Earth on an astronomical scale—much farther away than Sirius, for example. Orion will still be recognizable long after most of the other constellations—composed of relatively nearby stars—have distorted into new configurations, with the exception of a few of its stars eventually exploding as supernovae, for example Betelgeuse, which is predicted to explode sometime in the next million years. See also References External links |
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[SOURCE: https://en.wikipedia.org/wiki/Folk_saint] | [TOKENS: 2625] |
Contents Folk saint Folk saints are dead people or other spiritually powerful entities (such as indigenous spirits) venerated as saints, but not officially canonized. Since they are saints of the "folk", or the populus, they are also called popular saints. Like officially recognized saints, folk saints are considered intercessors with God, but many are also understood to act directly in the lives of their devotees. Frequently, their actions in life, as well as in death, distinguish folk saints from their canonized counterparts: official doctrine would consider many of them sinners and false idols. Their ranks are filled by folk healers, indigenous spirits, and folk heroes. Folk saints occur throughout the Catholic world, and they are especially popular in Latin America, where most have small followings; a few are celebrated at the national or even international level. Origins In the pre-Christian Abrahamic tradition, the prophets and holy people who were honored with shrines were identified by popular acclaim rather than official designation. In fact, the Islamic counterparts of the Christian saints, associated most closely with Sufism, are still identified this way. Early Christians followed in the same tradition when they visited the shrines of martyrs to ask for intercession with God. Thus, there is a long tradition for the veneration of unofficial saints, and modern folk saints continue to reach popularity in much the same way as ever. Tales of miracles or good works performed during the person's life are spread by word of mouth, and, according to anthropologist Octavio Ignacio Romano, "if exceptional fame is achieved, it may happen that after his [or her] death the same cycle of stories told during life will continue to be repeated." Popularity is likely to increase if new miracles continue to be reported after death. Hispanic studies professor Frank Graziano explains: [M]any folk devotions begin through the clouding of the distinction between praying for and praying to a recently deceased person. If several family members and friends pray at someone's tomb, perhaps lighting candles and leaving offerings, their actions arouse the curiosity of others. Some give it a try—the for and the to begin intermingling—because the frequent visits to the tomb suggest that the soul of its occupant may be miraculous. As soon as miracles are announced, often by family members and friends, newcomers arrive to send up prayers, now to the miraculous soul, with the hope of having their requests granted. This initial rise to fame follows much the same trajectory as that of the official saints. Professor of Spanish Kathleen Ann Myers writes that Rose of Lima, the first canonized American saint, attracted "mass veneration beginning almost at the moment of the mystic's death." Crowds of people appeared at her funeral, where some even cut off pieces of her clothing to keep as relics. A lay religious movement quickly developed with Rosa de Lima at the center but she was not officially canonized until half of a century later. In the meantime, she was essentially a folk saint. As the Church spread, it became more influential in regions that celebrated deities and heroes that were not part of Catholic tradition. Many of those figures were incorporated into a local variety of Catholicism: the ranks of official saints then came to include a number of non-Catholics or even fictional persons. Church leaders made an effort in 1969 to purge such figures from the official list of saints, though at least some probably remain. Many folk saints have their origins in this same mixing of Catholic traditions and local cultural and religious traditions. To distinguish canonized saints from folk saints, the latter are sometimes called animas or "spirits" instead of saints. Local character Folk saints tend to come from the same communities as their followers. In death, they are said to continue as active members of their communities, remaining embedded within a system of reciprocity that reaches beyond the grave. Devotees offer prayers to the folk saints and present them with offerings, and folk saints repay the favors by dispensing small miracles. Many folk saints inhabit marginalized communities, the needs of which are more worldly than others; they therefore frequently act in a more worldly, more pragmatic, less dogmatic fashion than their official counterparts. Devotion to folk saints, then, frequently takes on a distinctly local character, a result of the syncretic mixing of traditions and the particular needs of the community. The contrast between the manner in which Latin American and European folk saints are said to intercede in the lives of their followers provides a good illustration. In Western Europe, writes anthropologist and religious historian William A. Christian, "the more pervasive influence of scientific medicine, the comparative stability of Western European governments and above all, the more effective presence of the institutional Church" have meant that unofficial holy people generally work within established doctrine. Latin American holy persons, on the other hand, often stray much further from official canon. Whereas European folk saints serve merely as messengers of the divine, their Latin American counterparts frequently act directly in the lives of their devotees. During the Counter-Reformation in Europe, the Council of Trent released a decree "On the Invocation, Veneration, and Relics, of Saints, and on Sacred Images", which explained that, in Roman Catholic doctrine, images and relics of the saints are to be used by worshipers to help them contemplate the saints and the virtues that they represent but that those images and relics do not actually embody the saints. In the same way, folk saints in Europe are seen as intermediaries between penitents and the divine but are not considered powerful in and of themselves. A shrine may be built "that becomes the location for the fulfillment of the village's calendrical obligations and critical supplications to the shrine image—the village's divine protector," Christian writes, but "in this context the shrine image and the site of its location are of prime importance; the seer merely introduces it, and is not himself or herself the focal point of the worship." In pre-Columbian Mesoamerican tradition, on the other hand, representation meant embodiment of these holy figures rather than mere resemblance, as it did in Europe. Thus, pre-Hispanic Mexican and Central American images were understood to actually take on the character and spirit of the deities they represented, a perspective that was considered idolatry by European Catholics. As the inheritors of this tradition, folk saints of the region often are seen to act directly in the lives of their devotees rather than serving as mere intermediaries, and they are themselves venerated. Visitors frequently treat the representations of folk saints as real people, observing proper etiquette for speaking to a socially superior person or to a friend depending on the spirit's disposition—shaking hands, or offering it a cigarette or a drink. The popularity of a particular folk saint also depends on the changing dynamics and needs of the community over time. The popular devotion to Yevgeny Rodionov provides an example. Rodionov was a Russian soldier who was killed by rebels in Chechnya after he reportedly refused to renounce his religion or remove a cross he wore around his neck. He is not recognized by the Russian Orthodox Church as an official saint; yet, within a few years of his death, he had gained a popular following: his image appeared in homes and churches around Russia, his hometown started drawing pilgrims, and he began to receive prayers and requests for intercession. Rodionov became a favorite folk saint for soldiers and came to represent Russian nationalism at a time of conflict when the country was still reeling from the dissolution of the Soviet Union. As one journalist observed in 2003, his death and transition into the role of a folk saint served "to fill a nationalist hunger for popular heroes" when heroes were sorely needed. Devotions A devotee might visit the shrine of a folk saint for any number of reasons, including general requests for good health and good luck, the lifting of a curse, or protection on the road, but most folk saints have specialties for which their help is sought. Difunta Correa, for example, specializes in helping her followers acquire new homes and businesses. Juan Bautista Morillo helps gamblers in Venezuela,[citation needed] and Juan Soldado watches over border crossings between Mexico and the United States. This practice is not so different from that of canonized saints—St. Benedict, for example, is the patron saint of agricultural workers—but it would be hard to find a canonized saint to look after narcotics traffickers, as does Jesús Malverde. In fact, a number of folk saints attract devotees precisely because they respond to requests that the official saints are unlikely to answer. As Griffith writes, "One needs ask for help where the help is likely to be effective." So long as followers come before them with faith and perform the proper devotions, some folk saints are as willing to place a curse on a person as to lift one.[citation needed] An offering to a folk saint might include the same votive candles and ex-votos (tributes of thanks) left at the shrines to canonized saints, but they also frequently include other items that reflect something of the spirit's former life or personality. Thus, Difunta Correa, who died of thirst, is given bottles of water; Maximón and the spirit of Pancho Villa are both offered cigarettes and alcohol; teddy bears and toys are left at the tomb of a little boy called Carlitos in a cemetery in Hermosillo, Mexico. Likewise, prayers to folk saints are often paired with or incorporate aspects of the Rosary but (as with many canonized saints) special petitions have been composed for many of them, each prayer evoking the particular characteristics of the saint being addressed. Other local or regional idiosyncrasies also creep in. In parts of Mexico and Central America, for example, the aromatic resin copal is burned for the more syncretic spirits like Maximón, a practice that has its roots in the offerings made to indigenous deities. As long as the spirits come through for their followers, devotees will return. Word of mouth spreads news of cures and good fortune, and particularly responsive spirits are likely to gain a large following. Not all remain popular however, as in the case of Cutubilla whose cult has long since died out. While official saints remain canonized regardless of their popularity, folk saints that lose their devotees through their failure to respond to petitions might fade from memory entirely. Many folk saints are venerated exclusively in private homes by their devotees. For some devotion merely consists in the veneration of images or statues and the dissemination of prints or holy cards with the saint's image. This is because a folk saint may not have a special public shrine of their own and they are not represented by the institutional Church. Instead devotees usually erect small altars in their houses decorated with images of the saint, candles, flowers and other items. They also place holy cards in their cars or in their pockets to express their devotion and through distributing holy cards. Imagery plays an essential part in the establishing of a folk saint's cult and the maintenance of that devotion. Relationship with the Catholic Church In areas where the Catholic Church has greater power, it maintains more control over the devotional lives of its members. Thus, in Europe, folk devotions that are encouraged by the Church are quickly institutionalized, while those that are discouraged usually die out or continue only at reduced levels. For similar reasons, folk saints are more often venerated in poor and marginalized communities than in affluent ones. Nor are folk saints found in shrines to the canonical saints, though the reverse is often true: it is not uncommon for a folk saint's shrine to be decorated with images of other folk saints as well as members of the official Catholic communion. Shrines in the home, too, frequently include official and unofficial saints together. Graziano explains: Catholicism is not so much abandoned as expanded [by folk practitioners]; it is stretched to encompass exceptional resources. Whereas Catholicism ... defends a distinction between canonical and non-canonical or orthodox and heterodox, folk devotion intermingles these quite naturally and without reserve. Nonetheless, Catholics are generally discouraged from cultivating a devotion to folk saints (owing to a lack of certainty that the said person is in heaven or not or if doubt remains as to whether the person ever existed). In contrast, other folk saints such as San la Muerte and Santa Muerte are outright condemned by the Catholic Church as being evil and abominable. List of folk saints by country (known as "El Libertador") Venezuelans Latin America (known as Hermano Pule) Caracas, Venezuela Legendary folk saints USA (known as Sister Dulce of the poor) See also References This article incorporates material from the Citizendium article "Folk saint", which is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License but not under the GFDL. Sources External links |
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[SOURCE: https://en.wikipedia.org/wiki/List_of_Facebook_features] | [TOKENS: 9266] |
Contents List of Facebook features Facebook is a social-network service website launched on February 4, 2004, by Mark Zuckerberg. The following is a list of software and technology features that can be found on the Facebook website and mobile app and are available to users of the social media site. Facebook structure The news feed is the primary system through which users are exposed to content posted on the network. Using a secret method (initially known as EdgeRank), Facebook selects a handful of updates to actually show users every time they visit their feed, out of an average of 1500 updates they can potentially receive. On September 6, 2006, Ruchi Sanghvi announced a new home page feature called News Feed. Originally, when users logged into Facebook, they were presented with a customizable version of their own profile. The new layout, by contrast, created an alternative home page in which users saw a constantly updated list of their friends' Facebook activity. News Feed highlights information that includes profile changes, upcoming events, and birthdays, among other updates. This has enabled spammers and other users to manipulate these features by creating illegitimate events or posting fake birthdays to attract attention to their profile or cause. News Feed also shows conversations taking place between the walls of a user's friends. An integral part of the News Feed interface is the Mini Feed, a news stream on the user's profile page that shows updates about that user. Unlike in the News Feed, the user can delete events from the Mini Feed after they appear so that they are no longer visible to profile visitors. In 2011, Facebook updated the News Feed to show top stories and most recent stories in one feed, and the option to highlight stories to make them top stories, as well as to un-highlight stories. In response to users' criticism, Facebook later updated the News Feed to allow users to view recent stories first. Initially, the addition of the News Feed caused some discontent among Facebook users. Many users complained that the News Feed was too cluttered with excess information. Others were concerned that the News Feed made it too easy for other people to track activities like changes in relationship status, events, and conversations with other users. This tracking is often casually referred to as "Facebook-Stalking". In response to this dissatisfaction, creator Mark Zuckerberg issued an apology for the site's failure to include appropriate customizable privacy features. Thereafter, users were able to control what types of information were shared automatically with friends. Currently, users may prevent friends from seeing updates about several types of especially private activities, although other events are not customizable in this way. With the introduction of the "New Facebook" in early February 2010 came a complete redesign of the pages, several new features and changes to News Feeds. On their personal Feeds (now integrated with Walls), users were given the option of removing updates from any application as well as choosing the size they show up on the page. Furthermore, the community feed (containing recent actions by the user's friends) contained options to instantly select whether to hear more or less about certain friends or applications. On March 7, 2013, Facebook announced a redesigned newsfeed. In 2022, Facebook's parent company, Meta Platforms, announced it is renaming the "News Feed" to simply be named "Feed". "Friending" someone on the platform is the act of sending another user a "friend request" on Facebook. The two people are Facebook friends once the receiving party accepts the friend request. In addition to accepting the request, the user has the option of declining the friend request or hiding it using the "Not Now" feature. Deleting a friend request removes the request, but does allow the sender to resend it in the future. The "Not Now" feature hides the request but does not delete it, allowing the receiver to revisit the request at a later date. It is also possible to remove a user from one's friends, which is referred to as "unfriending" by Facebook. Many Facebook users also refer to the process as "de-friending". "Unfriend" was New Oxford American Dictionary's word of the year in 2009. Facebook does not notify a user if they have been unfriended, but there are scripts that provide this functionality. There has also been a study on why Facebook users unfriend, which found that differences, especially between ages, and few mutual friendships were the dominant factors correlated with unfriending, all of which mirrors the decline of physical-world relationships. Facebook profiles also have advanced privacy features to restrict content to certain users, such as non-friends or persons on a specific list. The wall is the original profile space where Facebook users' content was displayed, until December 2011. It allowed the posting of messages, often short or temporal notes, for the user to see while displaying the time and date the message was written. A user's wall is visible to anyone with the ability to see their full profile, and friends' wall posts appear in the user's News Feed. In July 2007, Facebook allowed users to post attachments to the wall, whereas previously the wall was limited to text only. In May 2008, the Wall-to-Wall for each profile was limited to only 40 posts. Facebook later allowed users to insert HTML code in boxes attached to the wall via apps like Static FBML which has allowed marketers to track use of their fan pages with Google Analytics. The concept of tagging in status updates, an attempt to imitate Twitter, began September 14, 2009. This meant putting the name of a user, a brand, an event or a group in a post in such a way that it linked to the wall of the Facebook page being tagged, and made the post appear in news feeds for that page, as well as those of selected friends. This was first done using the "@" symbol followed by the person's name. Later, a numerical ID for the person could be used. Visually, this was displayed with bold text. Early in 2011, tagging in comments was added. In addition to postings by other users, the wall also displayed other events that happened to the user's profile. This included when information was changed, when they changed their profile picture, and when they connected with new people, among other things.[citation needed] The wall has been replaced by the Timeline profile layout, which was introduced in December 2011.[citation needed] In September 2011, Facebook introduced "Timeline" at its developer conference, intended to revamp users' profiles in order to show content based on year, month and date. "Cover" photos were introduced, taking up a significant portion of the top of pages, and a redesigned display of personal information such as friends, likes and photos appeared on the left-hand side, while story posts appeared on the right. The new design introduced flexible sizing for story posts in the feed, along with more prominent location and photo placement. The Timeline also encouraged scrolling, with constantly loading story posts of users' pasts. Timeline began gradually rolling out to users in New Zealand starting December 7, 2011, and was made officially available to all users worldwide on December 15. By January, the switch to Timeline became required for all users. In February 2012, Timeline became available for Facebook Pages. The like button, first enabled on February 9, 2009, enables users to easily interact with status updates, comments, photos, links shared by friends, videos and advertisements. Once clicked by a user, the designated content appears in the News Feeds of that user's friends, and the button also displays the number of other users who have liked the content, including a full or partial list of those users. The like button was extended to comments in June 2010. After extensive testing and years of questions from the public about whether it had an intention to incorporate a "Dislike" button, Facebook officially rolled out "Reactions" to users worldwide on February 24, 2016, letting users long-press on the like button for an option to use one of six pre-defined emotions, including "Like", "Love", "Haha", "Wow", "Sad", or "Angry" and for a limited time the following reactions, "Care", "Pride Flag", "Thankful". Reactions were also extended to comments in May 2017. In June 2017, in celebration of Pride month, Facebook introduced a rainbow flag as part of its Reactions options. The design of the reactions was updated in April 2019, with more frames comprising the icons' animations as well as a general graphical overhaul.[citation needed] Around September 2019 Facebook conducted a trial in Australia to hide the like count on posts. In 2020 during the COVID-19 outbreak, a "Care" reaction was added to Facebook. To mark the 30th anniversary of the GIF, Facebook has introduced a new feature enabling users to add GIFs to comments. The eagerly awaited feature can be accessed using the GIF button located beside the emoji picker. Users can choose from the available GIFs sourced from Facebook's GIF partners, but cannot upload other GIFs. GIFs aside, the comments feature also allow users to attach stickers. Facebook has a standard sticker set, whereby sticker options are categorised according to popular moods and activities such as "Happy", "Eating", and "Confused". In 2020, Facebook introduced "Make Your Avatar" which enables users to customize a virtual look-alike of yourself to use as stickers in comments as well as Messenger chats. Essentially Facebook's version of Snap's Bitmoji, Avatars have been since made available in Australia, New Zealand, Europe and Canada. In December 2015, an indicator was added to the comment area to show when a friend is typing a new comment. Facebook Messenger is an instant messaging service and software application. Originally developed as Facebook Chat in 2008, the company revamped its messaging service in 2010, and subsequently released standalone iOS and Android apps in August 2011. Over the years, Facebook has released new apps on a variety of different operating systems, launched a dedicated website interface, and separated the messaging functionality from the main Facebook app, requiring users to download the standalone apps. Facebook Messenger lets Facebook users send messages to each other. Complementing regular conversations, Messenger lets users make voice calls and video calls both in one-to-one interactions and in group conversations. Its Android app has integrated support for SMS and "Chat Heads", which are round profile photo icons appearing on-screen regardless of what app is open, while both apps support multiple accounts, conversations with optional end-to-end encryption, and playing "Instant Games", which are select games built into Messenger. Some features, including sending money and requesting transportation, are limited to the United States. In 2017, Facebook has added "Messenger Day", a feature that lets users share photos and videos in a story-format with all their friends with the content disappearing after 24 hours; Reactions, which lets users tap and hold a message to add a reaction through an emoji; and Mentions, which lets users in group conversations type @ to give a particular user a notification. In March 2015, Facebook announced that it would start letting businesses and users interact through Messenger with features such as tracking purchases and receiving notifications, and interacting with customer service representatives. It also announced that third-party developers could integrate their apps into Messenger, letting users enter an app while inside Messenger and optionally share details from the app into a chat. In April 2016, it introduced an API for developers to build chatbots into Messenger, for uses such as news publishers building bots to give users news through the service, and in April 2017, it enabled the M virtual assistant for users in the U.S., which scans chats for keywords and suggests relevant actions, such as its payments system for users mentioning money. Additionally, Facebook expanded the use of bots, incorporating group chatbots into Messenger as "Chat Extensions", adding a "Discovery" tab for finding bots, and enabling special, branded QR codes that, when scanned, take the user to a specific bot. In August 2018, Facebook discontinued users' ability to post to their Timeline using SMS. In September 2022, Facebook added the "Community Chats" function, allowing people in a Facebook group to chat between each other on Messenger and on the Messenger app. Notifications tell the user that something has been added to their profile page. Examples include: a message being shared on the user's wall or a comment on a picture of the user or on a picture that the user has previously commented on. Initially, notifications for events were limited to one per event; these were eventually grouped category-wise. For instance, 10 users having liked a user's picture now count for one notification, whereas in the earlier stages, these would have accounted for ten separate notifications. The number of notifications can be changed in the settings section, to a maximum of 99. There is a red notification counter at the top of the page, which if clicked displays the most recent ones. Facebook Groups can be created by individual users. Groups allow members to post content such as links, media, questions, events, editable documents, and comments on these items. Groups are used for collaboration and allow discussions, events, and numerous other activities. They are a way of enabling a number of people to come together online to share information and discuss specific subjects. They are increasingly used by clubs, companies and public sector organizations to engage with stakeholders, be they members of the public, employees, members, service users, shareholders or customers. Groups can have two different levels of privacy settings: In October 2010, there were version 0 (legacy) and version 1 (current) groups. Version 1 or "new" groups can contain the name of the group in their URL if the email address of the group is set. Groups do not have a RSS feed to export the wall or the member list, such as Pages or Events have, but third parties provide such service if the group is set to an "open" privacy setting. All groups have since been migrated to a single design. Applications Facebook events are a way for members to let friends know about upcoming events in their community and to organize social gatherings. Events require an event name, network, host name, event type, start time, location, and a guest list of friends invited. Events can be public or private. Private events cannot be found in searches and are by invitation only. People who have not been invited cannot view a private event's description, Wall, or photos. They also will not see any Feed stories about the event. When setting up an event the user can choose to allow friends to upload photos or videos. Note that unlike real world events, all events are treated as separate entities (when the reality is some events sit inside other events, going to one event would preclude going to another, and so on). In February 2011, Facebook began to use the hCalendar microformat to mark up events, and the hCard microformat for the events' venues, enabling the extraction of details to users' own calendar or mapping applications. Third parties facilitate events to be exported from Facebook pages to the iCalendar-format.[citation needed] In 2007, Facebook introduced the Facebook Marketplace, allowing users to post classified ads within sale, housing, and jobs categories. However, the feature never gained traction, and in 2009, control was transferred to Oodle, the platform powering the functionality. The feature was then eventually shut down in 2014. In October 2016, Facebook announced a new Marketplace, citing the growth of organized "buy and sell" Facebook Groups, and gave the new version a higher prominence in the main Facebook app, taking the navigation position previously held by Facebook Messenger. According to Facebook's internal data from 2019, the Marketplace used to only be a C2C platform but now there is a major B2C opportunity for US retailers. In June 2021, the European Commission and Competition and Markets Authority launched antitrust probes over concerns that Facebook's Marketplace took advantage of data from competing services that advertise on the platform and used it to gain "an undue competitive advantage". Facebook Notes was introduced on August 22, 2006, as a blogging platform offering users the ability to write notes, attach photos, and optionally import blog entries from external sources. The most known usage form of the Notes feature was the Internet meme "25 Random Things About Me", which involves writing 25 things about the user that their friends do not already know about them and using the tag function to ask 25 friends to do the same. The trend became popular in February 2009, with The New York Times discussing its sudden surge, noting that nearly five million notes were created for the purpose, a doubling of the feature's use in the previous week and larger than any other week in Facebook's history. In September 2015, the Notes feature received an update, bringing additional features, such as adding a cover photo and caption, the ability to resize photos, and text formatting options. The Notes feature became read-only on October 31, 2020 and then entirely disappeared without notice a few weeks later.[citation needed] Facebook announced Places on August 18, 2010. It is a feature that lets users check into Facebook using a mobile device to let a user's friends know where they are at the moment. In November 2010, Facebook announced "Deals", a subset of the Places offering, which allows for users to check in from restaurants, supermarkets, bars, and coffee shops using an app on a mobile device and then be rewarded discounts, coupons, and free merchandise. This feature is marketed as a digital version of a loyalty card or coupon where a customer gets rewarded for loyal buying behavior. On October 10, 2010, Places became available on BlackBerry, iPhone, and Android. Other users, including Windows Mobile users, must use an HTML5 browser to use Places via Facebook Touch Site. Facebook Places was reported discontinued on August 24, 2011, but was relaunched in November 2014, now including cover images, discovery sections, city/category landing pages, a deeper integration with the Location API, Graph Search queries and user generated content. The Facebook Platform provides a set of APIs and tools which enable third-party developers to integrate with the "open graph", whether through applications on Facebook.com or external websites and devices. Launched on May 24, 2007, Facebook Platform has evolved from enabling development just on Facebook.com to one also supporting integration across the web and devices. Facebook Platform Statistics as of May 2010: On August 29, 2007, Facebook changed the way in which the popularity of applications is measured, to give attention to the more engaging applications, following criticism that ranking applications only by the number of people who had installed the application was giving an advantage to the highly viral, yet useless applications. Tech blog Valleywag has criticized Facebook Applications, labeling them a "cornucopia of uselessness". Others have called for limiting third-party applications so the Facebook "user experience" is not degraded. Primarily attempting to create viral applications is a method that has certainly been employed by numerous Facebook application developers. Stanford University even offered a class in the Fall of 2007, entitled, Computer Science (CS) 377W: "Create Engaging Web Applications Using Metrics and Learning on Facebook". Numerous applications created by the class were highly successful, and ranked amongst the top Facebook applications, with some achieving over 3.5 million users in a month. In May 2010, Facebook began testing Questions, which is expected to compete with services such as Yahoo Answers. On March 24, 2011, Facebook announced that its new product, Facebook Questions, facilitates short, poll -like answers in addition to long-form responses, and also links directly to relevant items in Facebook's directory of "fan pages". Facebook allows users to upload photos, and to add them to albums. In December 2010, the company enabled facial recognition technology, helping users identify people to tag in uploaded photos. In May 2011, Facebook launched a feature to tag specific Facebook pages in photos, including brands, products, and companies. On mobile, Facebook introduced photo filters in August 2011. In May 2016, Facebook started allowing users to upload and view 360-degree photos. Mobile users will move their device around to navigate the environment, while website users will have to click and drag. According to Facebook in 2010, there were over 50 billion photos stored on the service. In May 2007, Facebook officially launched its video platform, allowing users to upload recorded videos or livestream videos from their webcams. The service supports the ability to "tag" friends in similar ways to photos. In December 2014, Facebook began rolling out functionality for business Pages to pin ("Feature") a video to the top of their Videos tab. In January 2015, Facebook published a report detailing a significant growth in video viewing on the platform, specifically highlighting the fact that Facebook has seen an average of one billion video views every day since June 2014. In September 2015, Facebook announced that it would begin showing view counts for publicly posted videos. A few weeks later, the company announced that users will be able to view 360-degree videos. On the website, users can click around to change the perspective, whereas mobile users can physically move their device to interact with the virtual space. The result is the work of a collaboration between Facebook and its Oculus division. In August 2015, Facebook began to allow users to live stream video. Streams appear on the News Feed, and users can comment on them in real-time. Live broadcasts are automatically saved as a video post to the streamer's page. The feature was positioned as a competitor to services such as Meerkat and Periscope. The feature was initially available only to verified public figures through the Facebook Mentions app (which is also exclusive to these users). Live streaming began to roll out for public use in January 2016, beginning with the Facebook iOS app in the United States. In April 2016, Facebook unveiled a live-streaming API, aimed to allow developers to use any device, including professional video cameras and drones, to integrate with the live-video streaming platform. Facebook also updated its mobile app to provide a dedicated section for showcasing current and recent live broadcasts. To drive its adoption, Facebook provided incentives to publishers and celebrities to perform live broadcasts, including monetary rewards. In March 2017, Facebook extended live-streaming support to PCs. In May, Facebook Live was updated on iOS to let two users livestream together, and the following month, Facebook added support for closed captioning to live video. This is limited to the CEA-608 standard, a notable difference from the automatic closed captioning available for Page videos that are recorded and then uploaded, due to difficulties in adapting the same standard at scale on the low-latency real-time nature for live content. At the end of 2017, Facebook Live was updated to offer support for livestreaming Facebook Messenger games. Facebook Live was used by the perpetrators of an incident in which four black young adults kidnapped and tortured a mentally disabled white male. All four were charged and convicted of hate crimes. Facebook Live was also used by Brenton Tarrant, perpetrator of the Christchurch mosque shootings to broadcast the attack on Al Noor Mosque. A total of 51 people were killed and another 40 were injured at Al Noor and in a subsequent attack at Linwood Islamic Centre. This video was viewed over 4,000 times and had 200 watching it live. Because of this, Facebook announced it would be considering restrictions on the service. The service was also used to broadcast the hostage taking during the Nakhon Ratchasima shootings, which ultimately left 30 people dead including the perpetrator and 58 others injured. A shooting spree in Memphis in September 2022 was livestreamed by the suspect, a 19-year-old male; witnesses who viewed the stream saw him entering a store and shooting at customers inside. Additionally, Ronnie McNutt, an army veteran, committed suicide on a Facebook Live stream, leading to the footage spreading outside of Facebook Live to other social media platforms, including TikTok and Instagram, also owned by Meta. During the same week as its tenth anniversary (in 2014), Facebook launched the Paper iPhone app. The app consists of two major features: Firstly, Facebook's News Feed is more graphic, as the app uses technology such as full-screen photos and video footage. Content is organized under headings such as "Creators" and "Planet"; secondly, Paper allows users to post statuses, photos, and "stories" to Facebook that has been described as a different, more presentation-focused design. Facebook Mentions, initially an iOS-only app, was released by the company in 2014. It allows public figures with a verified account to engage with their respective fanbases in a more concentrated experience. The app had been in testing with select celebrities for nearly a year before its launch. In September 2015, Facebook expanded the availability of the Mentions app to journalists and other verified pages, and also gave users of the app the ability to post exclusively to their Facebook followers rather than both followers and friends. The update also enabled the first livestreaming functionality through Facebook Live. Facebook Mentions became available on Android in January 2016. In December 2016, Facebook Live on Mentions received several updates, including comment moderation tools, broadcasting appearance customization, and editing features to remove unnecessary footage at the beginning or end of a broadcast. Facebook Moments was a private photo sharing app launched by Facebook in 2015 but discontinued on February 25, 2019. The app was powered by Facebook's facial recognition technology to group photos and let users easily share them. Facebook Podcast was unveiled in April and launched on June 22, 2021. The integration allows listeners to find, subscribe to and listen to shows within the Facebook platform. In addition to the podcast product, Facebook is also working on other audio-focused offerings like a virtual chatroom feature akin to Clubhouse and short-form audio posts dubbed "Soundbites". General features In November 2015, Facebook made changes to their text-only status update on Timeline to allow for adjustable text sizes (dynamic text) on mobile apps. Facebook Credits are a virtual currency users can use to buy gifts, and virtual goods in many games and applications on the Facebook platform. As of July 2010, users of Facebook can purchase Facebook credits in Australian Dollars, British Pounds, Canadian Dollars, Chilean peso, Colombian peso, Danish krone, Euro, Hong Kong dollar, Japanese yen, Norwegian krone, Swedish krona, Swiss franc, Turkish lira, US Dollars, and Venezuelan Bolivar. Facebook credits can be used on many popular games such as Happy Aquarium, Happy Island, Zoo Paradise, Happy Pets, Hello City, It Girl, FarmVille, and Mafia Wars. Facebook Credits went into its alpha stage in May 2009 and progressed into the beta stage in February 2010, which ended in January 2011. At that time, Facebook announced all Facebook game developers would be required to process payments only through Facebook Credits from July 1, 2011. In March 2011, Facebook created an official subsidiary to handle payments: Facebook Payments Inc. In June 2012, Facebook announced it would no longer use its own money system, Facebook Credits. Users with credits will see them converted into their own currencies. Facebook Credits was officially removed from Facebook in September 2013. Although like all other website apps Facebook made its presence on the smartphones as mentioned but also is present for the feature phones. As the company said that the feature phones dominate the American cell phone markets, hence an app was exclusively made for this purpose as well. Released in July 2013, Graph Search allows users to search within their network of friends for answers to natural language questions such as, "Movies my friends who like The Hobbit liked" and receive direct answers, rather than the list of websites that search engines usually provide. According to a June 2010 report by Network World, Facebook said that it was offering "experimental, non-production" support for IPv6, the long-anticipated upgrade to the Internet's main communications protocol. The news about Facebook's IPv6 support was expected; Facebook told Network World in February 2010, that it planned to support native IPv6 user requests "by the midpoint of this year". In a presentation at the Google IPv6 Implementors Conference, Facebook's network engineers said it was "easy to make [the] site available on v6". Facebook said it deployed dual-stack IPv4 and IPv6 support on its routers, and that it made no changes to its hosts in order to support IPv6. Facebook also said it was supporting an emerging encapsulation mechanism known as Locator/Identifier Separation Protocol (LISP), which separates Internet addresses from endpoint identifiers to improve the scalability of IPv6 deployments. "Facebook was the first major Web site on LISP (v4 and v6)", Facebook engineers said during their presentation.[citation needed] Facebook said that using LISP allowed them to deploy IPv6 services quickly with no extra cost. In addition, Facebook enabled IPv6 on its main domain names during World IPv6 Launch.[citation needed] Listen with Friends allows Facebook users to listen to music and discuss the tunes using Facebook Chat with friends at the same time. Users can also listen in as a group while one friend acts as a DJ. Up to 50 friends can listen to the same song at the same time, and chat about it. Every time a user begins listening to music with a friend, a "story will be posted to her/his friends" ticker and/or news feed. Users will have control over who will be able to see when they are listening with a friend through their App Settings page after installing the compatible music app. This feature was initially supported through Audizer.com, but as of August 2012, services were discontinued and the Facebook / Audizer splash page has been redirected to Facebook.com. Facebook chat supports numerous emoticons, like (^^^) for a shark. Recently, it has also become possible to post larger, animated images through Facebook's built in emotion system. At an event in April 2013, Mark Zuckerberg announced a new Android-based "Home" feature, which would show content from users' Facebook pages on the home page of their mobile phones, without having to open an app. Since Facebook's inception, users have had the ability to "poke" other users. The feature, its actual purpose never officially explained by the company, served as a quick way to attract the attention of another user. In a 2007 opinion article in The Guardian, Facebook explained to a question about the "poke" that "When we created the poke, we thought it would be cool to have a feature without any specific purpose. People interpret the poke in many different ways, and we encourage you to come up with your own meanings." The feature was never removed from Facebook; in December 2017, the company gave the button a significantly more prominent placement on users' profiles, along with new forms of quick interactions, including "hug", "wink" and "high-five", collectively all referred to as "Greetings". Many smartphones offer access to the Facebook services either through their respective web browsers or through mobile apps. The iPhone-compatible website was launched in August 2007, followed by a dedicated iOS app in July 2008. The early mobile website was severely limited in its feature set, only gaining the ability to post comments in late 2008, a year after launch. By 2009, other companies had developed Facebook mobile apps for Nokia, HTC, LG, Motorola, Samsung, Sony Ericsson, and Windows Mobile devices, though a significant portion of Facebook's userbase was still using the original mobile website. During the early success of app stores, Facebook gambled on the idea of a universal webpage rather than specific operating systems, choosing to maintain its primary focus on its mobile site. CEO Mark Zuckerberg told Fortune that such a decision was "probably one of the biggest mistakes we've ever made". While the app was experiencing significant criticism for software bugs and crashes, Facebook began its "Facebook for Every Phone" initiative in January 2011, designing an app for a large number of feature phones. As Android and iOS rose in popularity, Facebook shifted its focus, creating dedicated apps for each platform. However, Facebook was still not entirely convinced, using a "hybrid" solution of native computing code as a sort of "picture frame" for its mobile website. Mashable described it as a "one-size-fits-all nightmare". In October 2011, Facebook updated its iOS app with support for iPad, adding larger photos and enabling more functionality, including the ability to post status updates and photos. Finally, in 2012, the company relaunched its Android and iOS apps, going mobile-first and putting all of its resources into making an optimized experience for smartphones, including significant speed improvements. In the years since, the company has increasingly expanded the feature set of its apps, dedicating more resources and seeing its userbase shifting from the mobile web to its apps. Third-party companies also created Facebook apps for their platforms. Microsoft developed a Facebook app for their Windows Phone 7 platform in February 2012, Nokia offered a Facebook app on its Ovi Store for Nokia S60 devices in June 2009, while BlackBerry also offered a Facebook application for its software platform in September 2012. In December 2013, Facebook enabled a "Donate" button for charities and non-profit organizations to raise money. Approximately two years later, the company released a new fundraiser feature, exclusively allowing non-profits to set up campaign pages and collect payments. This was expanded in June 2016, when anyone could set up fundraisers on behalf of non-profit organizations, and again expanded in March 2017 to offer personal users in the United States the ability to raise money, as well as for Facebook Pages to add a "Donate" button to their Facebook Live video streams. In May, fundraisers were expanded with support for communities and sports teams, and subsequently, in September, expanded internationally for charities in Europe. "Status updates" (also called a "status") allows users to post messages for their friends to read. In turn, friends can respond with their own comments, as well as clicking the "Like" button. A user's most recent updates appear at the top of their Timeline/Wall and are also noted in the "Recently Updated" section of a user's friend list. Originally, the purpose of the feature was to allow users to inform their friends of their current "status", including feelings, whereabouts, or actions, where Facebook prompted the status update with "Username is"... and users filled in the rest. This feature first became available in September 2006, though on December 13, 2007, the requirement to start a status update with is was removed. The is updates were followed by the "What are you doing right now?" status update question; in March 2009, the question was changed to "What's on your mind?" In 2009, Facebook added the feature to tag certain friends (or groups, etc.) within one's status update by adding an @ character before their name, turning the friend's name into a link to their profile and including the message on the friend's wall. Tagging has since been updated to recognize friends' names by typing them into a status while a list of friends whose names match the inputted letters appears. A large percentage of the updates that are posted are humorous and as a result, many apps, websites and books have sprung up to help users to update their own. In September 2011, Facebook launched a "Subscribe" button, allowing users to follow public updates from people without requiring a Facebook friendship connection. The feature was expanded to Pages in July 2012, and to stories in the News Feed in August 2012. In September 2011, Facebook launched the "Ticker", a continually-updated feed on the right side of the screen showing friends' activities, including "likes", status updates, and comments. The feed was criticized by users for offering a quiet way to stalk users' every move, prompting the company to consider removing it in a March 2013 redesign, though never did. In December 2017, the company officially ended the "Ticker" feature, though quietly and without an announcement or explanation. Starting June 2009, Facebook lets users choose a username specifically for their profile, enabling them to share links bearing their own www.facebook.com/username URL address. There are limitations, however, to what usernames can be used, including only alphanumerical characters (A-Z, 0–9), a length of over five characters, only one username that is unique to the profile, and must adhere to Facebook's Statement of Rights and Responsibilities agreement. The following December, Facebook launched its own URL shortener based on the FB.me domain name. TechCrunch reported in February 2012 that Facebook would introduce a "Verified Account" concept, denoting official pages for public figures. Such pages gain more prominence in the "People To Subscribe To" suggestions lists. Persons with established stage names, such as Stefani Germanotta known as Lady Gaga, can also choose to use their specific stage name for their profile, with the real name in the profile's "About" page. However, at the time, the feature did not show any visual signs of distinction from other pages. In May 2013, the concept was updated to include a blue checkmark badge to highlight the account's Verified status. In October 2015, Facebook introduced a "gray badge" verification system for local businesses with physical addresses, with the gray color intended to differentiate from its typical blue checkmarks assigned to celebrities, public figures, sports teams and media organizations. On June 12, 2013, Facebook introduced its support for clickable hashtags to help users search for topics being actively discussed on the social network. In March 2014, some page administrators in Italy started being prompted to add an impressum to their Facebook page, described as "a legally mandated statement of the ownership and authorship of a document". In October 2014, Facebook announced that users could connect to the website through a Tor hidden service using the privacy-protecting Tor browser and encrypted using SSL. Announcing the feature, Facebook engineer Alec Muffett said that "Facebook's onion address provides a way to access Facebook through Tor without losing the cryptographic protections provided by the Tor cloud. [...] It provides end-to-end communication, from your browser directly into a Facebook datacenter." In November 2014, Facebook introduced "Say Thanks", an experience that lets user create personalized video greeting cards for friends on Facebook. In December 2014, Facebook announced that Pages run by businesses can display a so-called "call-to-action button" next to the page's like button. "Call to action" is a customizable button that lets page administrators add external links for easy visitor access to the business' primary objective, with options ranging from "Book Now", "Contact Us", "Use App", "Play Game", "Shop Now", "Sign Up", and "Watch Video". Initially only rolled out in the United States, the feature was expanded internationally in February 2015. In September 2017, Facebook began testing a "Snooze" button, letting users temporarily unfollow friends for 24 hours, 7 days or 30 days. The following December, the feature was enabled for all users, though the period of temporary unfollowing is specifically for 30 days. In response to decreased use of status updates on Facebook, the company began enabling "Did You Know?" social questionnaires in December 2017. The feature, which asks users to answer questions that are then shared as a status update, includes such questions as "The superpower I want most is...", "The first thing I'd do after winning the lottery is...", and "A guilty pleasure that I'm willing to admit to is..." In December 2017, Facebook announced "Sound Collection"; an archive of copyright- and payment-free soundtracks and audio effects its users can use in their videos. In an August 20 blogpost, Facebook's Chief Privacy Officer Erin Egan, and Director of Product Management David Baser, announced "Off-Facebook Activity", to be released in Ireland, South Korea, and Spain, before being rolled out globally. Egan and Baser outline that with the feature, "you can: A second blogpost on Facebook's Engineering website says that, while users will be able to "Choose to disconnect future off-Facebook activity" from their accounts, there will be a 48-hour window in which data from other websites will remain linked to the account." During the 48-hour window when incoming off-Facebook data is still linked to your account, "it may be used for measurement purposes and to make improvements to our ads systems". The Memories feature, introduced in late 2010, allows browsing ones timeline by year. A feature under the same name was introduced in June 2018, showing events from the same day of earlier years. Security On May 12, 2011, Facebook announced that it is launching several new security features designed to protect users from malware and from getting their accounts hijacked. Facebook will display warnings when users are about to be duped by clickjacking and cross-site scripting attacks in which they think they are following a link to an interesting news story or taking action to see a video and instead end up spamming their friends. Facebook also offers two-factor authentication called "login approvals", which, if turned on, will require users to enter a code whenever they log into the site from a new or unrecognized device. The code is sent via text message to the user's mobile phone. Facebook is partnering with the free Web of Trust safe surfing service to give Facebook users more information about the sites they are linking to from the social network. When a user clicks on a potentially malicious link, a warning box will appear that gives more information about why the site might be dangerous. The user can either ignore the warning or go back to the previous page. Removed features In February 2010, TechCrunch reported that Facebook was working to rewrite its messaging service to turn it into a "fully featured webmail product", dubbed "Project Titan". The feature, unofficially dubbed a "Gmail killer" internally, was launched on November 15, 2010, and allowed users to directly communicate with each other via Facebook using several different methods. Users could create their own "username@facebook.com" email address to communicate, use text messaging, or through the Facebook website or mobile app's instant messaging chat. All messages were contained within single threads in a unified inbox. The email service was terminated in February 2014 because of low uptake. Facebook Markup Language (FBML) was considered to be Facebook's own version of HTML. While many of the tags of HTML can be used in FBML, there were also important tags that could not be used, such as HTML, HEAD, and BODY. Also, JavaScript could not be used with FBML. According to the Facebook Markup Language (FBML) Developer's page, FBML is now deprecated. No new features will be added to FBML and developers are recommended to develop new applications utilizing HTML, JavaScript and CSS. FBML support ended January 1, 2012, and FBML was no longer functioning as of June 1, 2012. In August 2009, Facebook announced the rollout of a "lite" version of the site, optimized for users on slower or intermittent Internet connections. Facebook Lite offered fewer services, excluded most third-party applications and required less bandwidth. A beta version of the slimmed-down interface was released first to invited testers before a broader rollout across users in the United States, Canada, and India. It was announced on April 20, 2010, that support for the "lite" service had ended and that users would be redirected back to the normal, full content, Facebook website. The service was operational for only eight months. In June 2015, this feature was reintroduced as an app with a total size of less than 1 MB, primarily focusing markets where internet access is slow or limited. Facebook announced a pilot program called Deals, which offered online coupons and discounts from local businesses, at an event at its Palo Alto office on 3 November 2010. Deals launched on April 25, 2011, in five cities—Atlanta, Austin, Dallas, San Diego, and San Francisco—with the hope of expanding. This new offering was a direct competitor to other social commerce sites such as LivingSocial and Groupon for online coupons and deals-of-the-day. Facebook users were able to use Facebook Credits to purchase vouchers that could be redeemed for real goods and services. Deals expanded to Charlotte, St. Louis and Minneapolis in late June 2011. Facebook closed the Deals program on 26 August 2011, describing the product as a "test." References |
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[SOURCE: https://en.wikipedia.org/wiki/Israeli_literature] | [TOKENS: 1429] |
Contents Israeli literature Israeli literature is literature written by Israelis. Most works classed as Israeli literature are written in the Hebrew language, although some Israeli authors write in Yiddish, English, Arabic and Russian. History The foundations of modern Israel writing were laid by a group of literary pioneers from the Second Aliyah including Shmuel Yosef Agnon, the only Nobel Prize winner for literature in Hebrew and the only one for Israeli literature, Moshe Smilansky, Yosef Haim Brenner, David Shimoni, and Jacob Fichman. Until World War I, Hebrew literature was centered in Eastern Europe. After the war and the Russian Revolution many Hebrew writers found their way to mandatory Palestine, so that at the time, Palestinian writing was essentially a continuation of the European tradition. In 1921, 70 writers met in Tel Aviv and founded the Hebrew Writers' Association. About this time the first literary periodicals made their appearance—Ha-Adamah, edited by Brenner, and Ma'abarot, edited by Fichman. The 1920's and 1930's witnessed the emergence of mandatory Palestine as the dominant center of Hebrew literary activity. Majority of the pioneers of Hebrew literature were Zionists, and eventually made their way to mandatory Palestine. The great figures of the early part of the century—Bialik, Ahad Ha-Am, Tchernichovsky—all spent their last years in Tel Aviv, and although this was not the period of their greatest creativity, they exerted a great influence on younger Hebrew writers. Among the earliest modern Hebrew writers was a small minority of writers who were born in mandatory Palestine. This cadre includes Yitzhaq Shami and Yehuda Burla , Sepharadi Jews whose families migrated to Palestine in the 19th and 18th centuries, respectively. The writing of this group stands out for its authentic depiction of the Arab and Jewish population of mandatory Palestine, told from the vantage point of those who grew up in its midst. The most important writers of the first generation, S.Y. Agnon and Haim Hazaz, were deeply rooted in their European background, and served as links between the classical writers of the early decades of the Hebrew revival and the Hebrew writers in mandatory Palestine during the following generations. For the next generation of writers, the center of focus was mandatory Palestine, even when they were writing about other parts of the world. Their framework was the period of aliyah and, very often, life in the kibbutz. Among the outstanding names are Uri Zvi Greenberg and Avraham Shlonsky, who found in mandatory Palestine the antidote to the rootlessness of the Diaspora. The third generation of writers emerged around the time of the 1948 Arab–Israeli War. Its key figures (S. Yizhar, Moshe Shamir, Hanoch Bartov, Haim Gouri, Benjamin Tammuz, Aharon Megged) were all sabras or had been brought to the country at an early age. Strong influences now came in from other countries, especially Western. A group called the "Canaanites" even sought to deny the connection between Israelis and Jews elsewhere. But after 1948, a feeling of emptiness and of searching for new values was leading to experiments in exploring the Jewish past. The subsequent generation of the 1960s (A. B. Yehoshua, Amos Oz, Natan Yonatan, Yoram Kaniuk, Yaakov Shabtai) has endeavoured to place Israeli culture within a world context and stresses not so much the unique aspects of Jewish life and Israel as the universal. This school of writers often identifies itself with the protest literature of other countries. The following generation, writers who were born in the 1960s and 1970s and made their debut in the 1980s and 1990s, examined the basic questions of Jewish-Israeli existence by exposing the collective tensions in individual characters and fates. Notable writers from this era include Etgar Keret and Sayed Kashua. Apart from Hebrew writers, there is considerable creative productivity in Israel in other languages, notably in Yiddish. Before World War II, Warsaw, Moscow, and New York were the main centers of Yiddish activity. In Palestine there was still a certain hostility to the Yiddish language, which was felt as a challenge to the Hebrew revival. However, with World War II the whole picture changed. The European centers were liquidated by Hitler and Stalin, and the New York center declined. Immigration brought many of the leading Yiddish writers to Israel. Here the internal attitude relaxed and became friendly, in view of the Holocaust in Europe, on the one hand, and the secure position attained by Hebrew, on the other. Yiddish writing in Israel can be marked by generations, similar to those in Hebrew literature. The first consisted of writers such as David Pinski and Sholem Asch, who passed their last years in Israel. The second generation, led by Abraham Sutzkever, started its career in Eastern Europe but continued in Israel. The third generation was centered on "Young Israel", a modernist group of poets and prose writers, most of whom are kibbutz members, whose work has been influenced by the avant-garde schools of English and French writing. Yiddish writing in Israel is concentrated on the European Holocaust (the leading writer on this is Ka-Tzetnik), and life among new immigrants. Yiddish authors in Israel are organized in a Yiddish authors' association. The presence of Arabic-language literature in Israeli society can be initially attributed to Emile Habibi, an Israeli-Palestinian writer and a communist politician. In 1992, he was awarded the Israel Prize for Arabic literature. A fervent communist, Habibi helped created the Israeli Communist Party and established Al-Ittihad, a communist daily Arabic language newspaper published in Haifa. Habibi's works, while often a critique of Israeli society, are nevertheless part of Israeli culture. Publication of books in Israel By law, the Jewish National and University Library of the Hebrew University of Jerusalem receives two copies of each book published in Israel. In 2004 it reported that it received 6,436 new books. Most of them were published in Hebrew, and 89% those books published in Hebrew were original to the Hebrew language. Almost 8% of the 2004 crop were children's books and another 4% were textbooks. According to the type of publisher, the books were 55% commercial, 14% self-published, 10% governmental, 7% educational, and 14% published by other types of organizations. The orthodox and ultra-orthodox sector was responsible for 21% of the total titles. 2017 figures show that 17% of books were Torah-related, 16% were literature and 14% children's books. See also References External links |
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[SOURCE: https://en.wikipedia.org/wiki/Sponges] | [TOKENS: 10785] |
Contents Sponge Parazoa/Ahistozoa (sans Placozoa) Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (/pəˈrɪfərəˌ pɔː-/; meaning 'pore bearer'). They are sessile filter feeders that are bound to the seabed, and are one of the most ancient members of macrobenthos, with many historical species being important reef-building organisms. Sponges are multicellular organisms consisting of jelly-like mesohyl sandwiched between two thin layers of cells, and usually have tube-like bodies full of pores and channels that allow water to circulate through them. They have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process. They do not have complex nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes, usually via flagella movements of the so-called "collar cells". Sponges may be the sister group to all other animals, although the evidence for this relationship remains inconclusive. Fossil evidence of primitive sponges such as Otavia dates to as early as the Tonian period (around 800 Mya). The branch of zoology that studies sponges is spongiology. Etymology The term sponge derives from the Ancient Greek word σπόγγος spóngos. The scientific name Porifera is a neuter plural of the Modern Latin term porifer, which comes from the roots porus meaning "pore, opening", and -fer meaning "bearing or carrying". Overview Sponges are similar to other animals in that they are multicellular, heterotrophic, lack cell walls and produce sperm cells. Unlike other animals, they lack true tissues and organs. Some of them are radially symmetrical, but most are asymmetrical. The shapes of their bodies are adapted for maximal efficiency of water flow through the central cavity, where the water deposits nutrients and then leaves through a hole called the osculum. The single-celled choanoflagellates resemble the choanocyte cells of sponges which are used to drive their water flow systems and capture most of their food. This along with phylogenetic studies of ribosomal molecules have been used as morphological evidence to suggest sponges are the sister group to the rest of animals. A great majority are marine (salt-water) species, ranging in habitat from tidal zones to depths exceeding 8,800 m (5.5 mi), though there are freshwater species. All adult sponges are sessile, meaning that they attach to an underwater surface and remain fixed in place (i.e., do not travel). While in their larval stage of life, they are motile. Many sponges have internal skeletons of spicules (skeletal-like fragments of calcium carbonate or silicon dioxide), and/or spongin (a modified type of collagen protein). An internal gelatinous matrix called mesohyl functions as an endoskeleton, and it is the only skeleton in soft sponges that encrust such hard surfaces as rocks. More commonly, the mesohyl is stiffened by mineral spicules, by spongin fibers, or both. Most sponges (over 90% of all known species) are demosponges, which have the widest range of habitats (including all freshwater ones); they use spongin, silica spicules, or both, and some species have calcium carbonate exoskeletons. Calcareans have calcium carbonate spicules and, in some species, calcium carbonate exoskeletons; they are restricted to relatively shallow marine waters where production of calcium carbonate is easiest.: 179 The fragile hexactinellids or glass sponges use "scaffolding" of silica spicules and are restricted to polar regions or ocean depths where predators are rare. Fossils of all of these types have been found in rocks dated from 580 million years ago. In addition Archaeocyathids, whose fossils are common in rocks from 530 to 490 million years ago, are now regarded as a type of sponge. The smallest class of extant sponges are homoscleromorphs, which either have calcium carbonate spicules like the calcereans or are aspiculate, and found in shaded marine environments like caves and overhangs. Although most of the approximately 5,000–10,000 known species of sponges feed on bacteria and other microscopic food in the water, some host photosynthesizing microorganisms as endosymbionts, and these alliances often produce more food and oxygen than they consume. A few species of sponges that live in food-poor environments have evolved as carnivores that prey mainly on small crustaceans. Most sponges reproduce sexually, but they can also reproduce asexually. Sexually reproducing species release sperm cells into the water to fertilize ova released or retained by its mate or "mother"; the fertilized eggs develop into larvae which swim off in search of places to settle.: 183–185 Sponges are known for regenerating from fragments that are broken off, although this only works if the fragments include the right types of cells. Some species reproduce by budding. When environmental conditions become less hospitable to the sponges, for example as temperatures drop, many freshwater species and a few marine ones produce gemmules, "survival pods" of unspecialized cells that remain dormant until conditions improve; they then either form completely new sponges or recolonize the skeletons of their parents.: 120–127 The few species of demosponge that have entirely soft fibrous skeletons with no hard elements have been used by humans over thousands of years for several purposes, including as padding and as cleaning tools. By the 1950s, though, these had been overfished so heavily that the industry almost collapsed, and most sponge-like materials are now synthetic. Sponges and their microscopic endosymbionts are now being researched as possible sources of medicines for treating a wide range of diseases. Dolphins have been observed using sponges as tools while foraging. Distinguishing features Sponges constitute the phylum Porifera, and have been defined as sessile metazoans (multicelled immobile animals) that have water intake and outlet openings connected by chambers lined with choanocytes, cells with whip-like flagella.: 29 However, a few carnivorous sponges have lost these water flow systems and the choanocytes.: 39 All known living sponges can remold their bodies, as most types of their cells can move within their bodies and a few can change from one type to another. Even if a few sponges are able to produce mucus – which acts as a microbial barrier in all other animals – no sponge with the ability to secrete a functional mucus layer has been recorded. Without such a mucus layer their living tissue is covered by a layer of microbial symbionts, which can contribute up to 40–50% of the sponge wet mass. This inability to prevent microbes from penetrating their porous tissue could be a major reason why they have never evolved a more complex anatomy. Like cnidarians (jellyfish, etc.) and ctenophores (comb jellies), and unlike all other known metazoans, sponges' bodies consist of a non-living jelly-like mass (mesohyl) sandwiched between two main layers of cells. Cnidarians and ctenophores have simple nervous systems, and their cell layers are bound by internal connections and by being mounted on a basement membrane a thin fibrous mat, also known as a basal lamina. Sponges do not have a nervous system similar to that of vertebrates but may have one that is quite different. Their middle jelly-like layers have large and varied populations of cells, and some types of cells in their outer layers may move into the middle layer and change their functions. Basic structure A sponge's body is hollow and is held in shape by the mesohyl, a jelly-like substance made mainly of collagen and reinforced by a dense network of fibers also made of collagen. 18 distinct cell types have been identified. The inner surface is covered with choanocytes, cells with cylindrical or conical collars surrounding one flagellum per choanocyte. The wave-like motion of the whip-like flagella drives water through the sponge's body. All sponges have ostia, channels leading to the interior through the mesohyl, and in most sponges these are controlled by tube-like porocytes that form closable inlet valves. Pinacocytes, plate-like cells, form a single-layered external skin over all other parts of the mesohyl that are not covered by choanocytes, and the pinacocytes also digest food particles that are too large to enter the ostia, while those at the base of the animal are responsible for anchoring it. Other types of cells live and move within the mesohyl: Many larval sponges possess neuron-less eyes that are based on cryptochromes. They mediate phototaxic behavior. Glass sponges present a distinctive variation on this basic plan. Their spicules, which are made of silica, form a scaffolding-like framework between whose rods the living tissue is suspended like a cobweb that contains most of the cell types. This tissue is a syncytium that in some ways behaves like many cells that share a single external membrane, and in others like a single cell with multiple nuclei. Most sponges work rather like chimneys: they take in water at the bottom and eject it from the osculum at the top. Since ambient currents are faster at the top, the suction effect that they produce by Bernoulli's principle does some of the work for free. Sponges can control the water flow by various combinations of wholly or partially closing the osculum and ostia (the intake pores) and varying the beat of the flagella, and may shut it down if there is a lot of sand or silt in the water. Although the layers of pinacocytes and choanocytes resemble the epithelia of more complex animals, they are not bound tightly by cell-to-cell connections or a basal lamina (thin fibrous sheet underneath). The flexibility of these layers and re-modeling of the mesohyl by lophocytes allow the animals to adjust their shapes throughout their lives to take maximum advantage of local water currents.: 83 The simplest body structure in sponges is a tube or vase shape known as "asconoid", but this severely limits the size of the animal. The body structure is characterized by a stalk-like spongocoel surrounded by a single layer of choanocytes. If it is simply scaled up, the ratio of its volume to surface area increases, because surface increases as the square of length or width while volume increases proportionally to the cube. The amount of tissue that needs food and oxygen is determined by the volume, but the pumping capacity that supplies food and oxygen depends on the area covered by choanocytes. Asconoid sponges seldom exceed 1 mm (0.039 in) in diameter. Some sponges overcome this limitation by adopting the "syconoid" structure, in which the body wall is pleated. The inner pockets of the pleats are lined with choanocytes, which connect to the outer pockets of the pleats by ostia. This increase in the number of choanocytes and hence in pumping capacity enables syconoid sponges to grow up to a few centimeters in diameter. The "leuconoid" pattern boosts pumping capacity further by filling the interior almost completely with mesohyl that contains a network of chambers lined with choanocytes and connected to each other and to the water intakes and outlet by tubes. Leuconid sponges grow to over 1 m (3.3 ft) in diameter, and the fact that growth in any direction increases the number of choanocyte chambers enables them to take a wider range of forms, for example, "encrusting" sponges whose shapes follow those of the surfaces to which they attach. All freshwater and most shallow-water marine sponges have leuconid bodies. The networks of water passages in glass sponges are similar to the leuconid structure. In all three types of structure, the cross-section area of the choanocyte-lined regions is much greater than that of the intake and outlet channels. This makes the flow slower near the choanocytes and thus makes it easier for them to trap food particles. For example, in Leuconia, a small leuconoid sponge about 10 centimetres (3.9 in) tall and 1 centimetre (0.39 in) in diameter, water enters each of more than 80,000 intake canals at 6 cm per minute. However, because Leuconia has more than 2 million flagellated chambers whose combined diameter is much greater than that of the canals, water flow through chambers slows to 3.6 cm per hour, making it easy for choanocytes to capture food. All the water is expelled through a single osculum at about 8.5 cm per second, fast enough to carry waste products some distance away. In zoology, a skeleton is any fairly rigid structure of an animal, irrespective of whether it has joints and irrespective of whether it is biomineralized. The mesohyl functions as an endoskeleton in most sponges, and is the only skeleton in soft sponges that encrust hard surfaces such as rocks. More commonly the mesohyl is stiffened by mineral spicules, by spongin fibers or both. Spicules, which are present in most but not all species, may be made of silica or calcium carbonate, and vary in shape from simple rods to three-dimensional "stars" with up to six rays. Spicules are produced by sclerocyte cells, and may be separate, connected by joints, or fused. Some sponges also secrete exoskeletons that lie completely outside their organic components. For example, sclerosponges ("hard sponges") have massive calcium carbonate exoskeletons over which the organic matter forms a thin layer with choanocyte chambers in pits in the mineral. These exoskeletons are secreted by the pinacocytes that form the animals' skins. Vital functions Although adult sponges are fundamentally sessile animals, some marine and freshwater species can move across the sea bed at speeds of 1–4 mm (0.039–0.157 in) per day, as a result of amoeba-like movements of pinacocytes and other cells. A few species can contract their whole bodies, and many can close their oscula and ostia. Juveniles drift or swim freely, while adults are stationary. Sponges do not have distinct circulatory, respiratory, digestive, and excretory systems – instead, the water flow system supports all these functions. They filter food particles out of the water flowing through them. Particles larger than 50 micrometers cannot enter the ostia and pinacocytes consume them by phagocytosis (engulfing and intracellular digestion). Particles from 0.5 μm to 50 μm are trapped in the ostia, which taper from the outer to inner ends. These particles are consumed by pinacocytes or by archaeocytes which partially extrude themselves through the walls of the ostia. Bacteria-sized particles, below 0.5 micrometers, pass through the ostia and are caught and consumed by choanocytes. Since the smallest particles are by far the most common, choanocytes typically capture 80% of a sponge's food supply. Archaeocytes transport food packaged in vesicles from cells that directly digest food to those that do not. At least one species of sponge has internal fibers that function as tracks for use by nutrient-carrying archaeocytes, and these tracks also move inert objects. It used to be claimed that glass sponges could live on nutrients dissolved in sea water and were very averse to silt. However, a study in 2007 found no evidence of this and concluded that they extract bacteria and other micro-organisms from water very efficiently (about 79%) and process suspended sediment grains to extract such prey. Collar bodies digest food and distribute it wrapped in vesicles that are transported by dynein "motor" molecules along bundles of microtubules that run throughout the syncytium. Sponges' cells absorb oxygen by diffusion from water into cells as water flows through body, into which carbon dioxide and other soluble waste products such as ammonia also diffuse. Archeocytes remove mineral particles that threaten to block the ostia, transport them through the mesohyl and generally dump them into the outgoing water current, although some species incorporate them into their skeletons. In waters where the supply of food particles is very poor, some species prey on crustaceans and other small animals. As of 2014, a total of 137 species had been discovered. Most belong to the family Cladorhizidae, but a few members of the Guitarridae and Esperiopsidae are also carnivores. In most cases, little is known about how they actually capture prey, although some species are thought to use either sticky threads or hooked spicules. Most carnivorous sponges live in deep waters, up to 8,840 m (5.49 mi), and the development of deep-ocean exploration techniques is expected to lead to the discovery of several more. However, one species has been found in Mediterranean caves at depths of 17–23 m (56–75 ft), alongside the more usual filter-feeding sponges. The cave-dwelling predators capture crustaceans under 1 mm (0.039 in) long by entangling them with fine threads, digest them by enveloping them with further threads over the course of a few days, and then return to their normal shape; there is no evidence that they use venom. Most known carnivorous sponges have completely lost the water flow system and choanocytes. However, the genus Chondrocladia uses a highly modified water flow system to inflate balloon-like structures that are used for capturing prey. Freshwater sponges often host green algae as endosymbionts within archaeocytes and other cells and benefit from nutrients produced by the algae. Many marine species host other photosynthesizing organisms, most commonly cyanobacteria but in some cases dinoflagellates. Symbiotic cyanobacteria may form a third of the total mass of living tissue in some sponges, and some sponges gain 48% to 80% of their energy supply from these micro-organisms. In 2008, a University of Stuttgart team reported that spicules made of silica conduct light into the mesohyl, where the photosynthesizing endosymbionts live. Sponges that host photosynthesizing organisms are most common in waters with relatively poor supplies of food particles and often have leafy shapes that maximize the amount of sunlight they collect. A recently discovered carnivorous sponge that lives near hydrothermal vents hosts methane-eating bacteria and digests some of them. Sponges do not have the complex immune systems of most other animals. However, they reject grafts from other species but accept them from other members of their own species. In a few marine species, gray cells play the leading role in rejection of foreign material. When invaded, they produce a chemical that stops movement of other cells in the affected area, thus preventing the intruder from using the sponge's internal transport systems. If the intrusion persists, the grey cells concentrate in the area and release toxins that kill all cells in the area. The "immune" system can stay in this activated state for up to three weeks. Sponges have three asexual methods of reproduction: after fragmentation, by budding, and by producing gemmules. Fragments of sponges may be detached by currents or waves. They use the mobility of their pinacocytes and choanocytes and reshaping of the mesohyl to re-attach themselves to a suitable surface and then rebuild themselves as small but functional sponges over the course of several days. The same capabilities enable sponges that have been squeezed through a fine cloth to regenerate.: 239 A sponge fragment can only regenerate if it contains both collencytes to produce mesohyl and archeocytes to produce all the other cell types. A very few species reproduce by budding.: 90–94 Gemmules are "survival pods" which a few marine sponges and many freshwater species produce by the thousands when dying and which some, mainly freshwater species, regularly produce in autumn. Spongocytes make gemmules by wrapping shells of spongin, often reinforced with spicules, round clusters of archeocytes that are full of nutrients.: 87–88 Freshwater gemmules may also include photosynthesizing symbionts. The gemmules then become dormant, and in this state can survive cold, drying out, lack of oxygen and extreme variations in salinity. Freshwater gemmules often do not revive until the temperature drops, stays cold for a few months and then reaches a near-"normal" level. When a gemmule germinates, the archeocytes round the outside of the cluster transform into pinacocytes, a membrane over a pore in the shell bursts, the cluster of cells slowly emerges, and most of the remaining archeocytes transform into other cell types needed to make a functioning sponge. Gemmules from the same species but different individuals can join forces to form one sponge.: 89–90 Some gemmules are retained within the parent sponge, and in spring it can be difficult to tell whether an old sponge has revived or been "recolonized" by its own gemmules. Most sponges are hermaphrodites (function as both sexes simultaneously), although sponges have no gonads (reproductive organs). Sperm are produced by choanocytes or entire choanocyte chambers that sink into the mesohyl and form spermatic cysts while eggs are formed by transformation of archeocytes, or of choanocytes in some species. Each egg generally acquires a yolk by consuming "nurse cells". During spawning, sperm burst out of their cysts and are expelled via the osculum. If they contact another sponge of the same species, the water flow carries them to choanocytes that engulf them but, instead of digesting them, metamorphose to an ameboid form and carry the sperm through the mesohyl to eggs, which in most cases engulf the carrier and its cargo.: 77 A few species release fertilized eggs into the water, but most retain the eggs until they hatch. By retaining the eggs, the parents can transfer symbiotic microorganisms directly to their offspring through vertical transmission, while the species who release their eggs into the water has to acquire symbionts horizontally (a combination of both is probably most common, where larvae with vertically transmitted symbionts also acquire others horizontally). There are four types of larvae, but all are lecithotrophic (non-feeding) balls of cells with an outer layer of cells whose flagella or cilia enable the larvae to move. After swimming for a few days the larvae sink and crawl until they find a place to settle. Most of the cells transform into archeocytes and then into the types appropriate for their locations in a miniature adult sponge.: 77 Glass sponge embryos start by dividing into separate cells, but once 32 cells have formed they rapidly transform into larvae that externally are ovoid with a band of cilia round the middle that they use for movement, but internally have the typical glass sponge structure of spicules with a cobweb-like main syncitium draped around and between them and choanosyncytia with multiple collar bodies in the center. The larvae then leave their parents' bodies. The cytological progression of porifera oogenesis and spermatogenesis (gametogenesis) is very similar to that of other metazoa. Most of the genes from the classic set of meiotic genes, including genes for DNA recombination and double-strand break repair, that are conserved in eukaryotes are expressed in the sponges (e.g. Geodia hentscheli and Geodia phlegraei). Since porifera are considered to be the earliest divergent animals, these findings indicate that the basic toolkit of meiosis including capabilities for recombination and DNA repair were present early in eukaryote evolution. Sponges in temperate regions live for at most a few years, but some tropical species and perhaps some deep-ocean ones may live for 200 years or more. Some calcified demosponges grow by only 0.2 mm (0.0079 in) per year and, if that rate is constant, specimens 1 m (3.3 ft) wide must be about 5,000 years old. Some sponges start sexual reproduction when only a few weeks old, while others wait until they are several years old. Adult sponges lack neurons or any other kind of nervous tissue. However, most species have the ability to perform movements that are coordinated all over their bodies, mainly contractions of the pinacocytes, squeezing the water channels and thus expelling excess sediment and other substances that may cause blockages. Some species can contract the osculum independently of the rest of the body. Sponges may also contract in order to reduce the area that is vulnerable to attack by predators. In cases where two sponges are fused, for example if there is a large but still unseparated bud, these contraction waves slowly become coordinated in both of the "Siamese twins". The coordinating mechanism is unknown, but may involve chemicals similar to neurotransmitters. However, glass sponges rapidly transmit electrical impulses through all parts of the syncytium, and use this to halt the motion of their flagella if the incoming water contains toxins or excessive sediment. Myocytes are thought to be responsible for closing the osculum and for transmitting signals between different parts of the body. Sponges contain genes very similar to those that contain the "recipe" for the post-synaptic density, an important signal-receiving structure in the neurons of all other animals. However, in sponges these genes are only activated in "flask cells" that appear only in larvae and may provide some sensory capability while the larvae are swimming. This raises questions about whether flask cells represent the predecessors of true neurons or are evidence that sponges' ancestors had true neurons but lost them as they adapted to a sessile lifestyle. Ecology Sponges are worldwide in their distribution, living in a wide range of ocean habitats, from the polar regions to the tropics. Most live in quiet, clear waters, because sediment stirred up by waves or currents would block their pores, making it difficult for them to feed and breathe. The greatest numbers of sponges are usually found on firm surfaces such as rocks, but some sponges can attach themselves to soft sediment by means of a root-like base. Sponges are more abundant but less diverse in temperate waters than in tropical waters, possibly because organisms that prey on sponges are more abundant in tropical waters. Glass sponges are the most common in polar waters and in the depths of temperate and tropical seas, as their very porous construction enables them to extract food from these resource-poor waters with the minimum of effort. Demosponges and calcareous sponges are abundant and diverse in shallower non-polar waters. The different classes of sponge live in different ranges of habitat: Sponges with photosynthesizing endosymbionts produce up to three times more oxygen than they consume, as well as more organic matter than they consume. Such contributions to their habitats' resources are significant along Australia's Great Barrier Reef but relatively minor in the Caribbean. Many sponges shed spicules, forming a dense carpet several meters deep that keeps away echinoderms which would otherwise prey on the sponges. They also produce toxins that prevent other sessile organisms such as bryozoans or sea squirts from growing on or near them, making sponges very effective competitors for living space. One of many examples includes ageliferin, which has antibacterial action and causes biofilms to dissolve. A few species, including the Caribbean fire sponge Tedania ignis, cause a severe rash in humans who handle them. Turtles and some fish feed mainly on sponges. It is often said that sponges produce chemical defenses against such predators. However, experiments have been unable to establish a relationship between the toxicity of chemicals produced by sponges and how they taste to fish, which would diminish the usefulness of chemical defenses as deterrents. Predation by fish may even help to spread sponges by detaching fragments. However, some studies have shown fish showing a preference for non-chemically-defended sponges, and another study found that high levels of coral predation did predict the presence of chemically defended species. Glass sponges produce no toxic chemicals, and live in very deep water where predators are rare. Spongeflies, also known as spongillaflies (Neuroptera, Sisyridae), are specialist predators of freshwater sponges. The female lays her eggs on vegetation overhanging water. The larvae hatch and drop into the water where they seek out sponges to feed on. They use their elongated mouthparts to pierce the sponge and suck the fluids within. The larvae of some species cling to the surface of the sponge while others take refuge in the sponge's internal cavities. The fully grown larvae leave the water and spin a cocoon in which to pupate. The Caribbean chicken-liver sponge Chondrilla nucula secretes toxins that kill coral polyps, allowing the sponges to grow over the coral skeletons. Others, especially in the family Clionaidae, use corrosive substances secreted by their archeocytes to tunnel into rocks, corals and the shells of dead mollusks. Sponges may remove up to 1 m (3.3 ft) per year from reefs, creating visible notches just below low-tide level. Caribbean sponges of the genus Aplysina suffer from Aplysina red band syndrome. This causes Aplysina to develop one or more rust-colored bands, sometimes with adjacent bands of necrotic tissue. These lesions may completely encircle branches of the sponge. The disease appears to be contagious and impacts approximately ten percent of A. cauliformis on Bahamian reefs. The rust-colored bands are caused by a cyanobacterium, but it is unknown whether this organism actually causes the disease. In addition to hosting photosynthesizing endosymbionts, sponges are noted for their wide range of collaborations with other organisms. The relatively large encrusting sponge Lissodendoryx colombiensis is most common on rocky surfaces, but has extended its range into seagrass meadows by letting itself be surrounded or overgrown by seagrass sponges, which are distasteful to the local starfish and therefore protect Lissodendoryx against them; in return, the seagrass sponges get higher positions away from the sea-floor sediment. Shrimps of the genus Synalpheus form colonies in sponges, and each shrimp species inhabits a different sponge species, making Synalpheus one of the most diverse crustacean genera. Specifically, Synalpheus regalis utilizes the sponge not only as a food source, but also as a defense against other shrimp and predators. As many as 16,000 individuals inhabit a single loggerhead sponge, feeding off the larger particles that collect on the sponge as it filters the ocean to feed itself. Other crustaceans such as hermit crabs commonly have a specific species of sponge, Pseudospongosorites, grow on them as both the sponge and crab occupy gastropod shells until the crab and sponge outgrow the shell, eventually resulting in the crab using the sponge's body as protection instead of the shell until the crab finds a suitable replacement shell. Most sponges are detritivores which filter organic debris particles and microscopic life forms from ocean water. In particular, sponges occupy an important role as detritivores in coral reef food webs by recycling detritus to higher trophic levels. The hypothesis has been made that coral reef sponges facilitate the transfer of coral-derived organic matter to their associated detritivores via the production of sponge detritus, as shown in the diagram. Several sponge species are able to convert coral-derived DOM into sponge detritus, and transfer organic matter produced by corals further up the reef food web. Corals release organic matter as both dissolved and particulate mucus, as well as cellular material such as expelled Symbiodinium. Organic matter could be transferred from corals to sponges by all these pathways, but DOM likely makes up the largest fraction, as the majority (56 to 80%) of coral mucus dissolves in the water column, and coral loss of fixed carbon due to expulsion of Symbiodinium is typically negligible (0.01%) compared with mucus release (up to ~40%). Coral-derived organic matter could also be indirectly transferred to sponges via bacteria, which can also consume coral mucus. Besides a one to one symbiotic relationship, it is possible for a host to become symbiotic with a microbial consortium, resulting in a diverse sponge microbiome. Sponges are able to host a wide range of microbial communities that can also be very specific. The microbial communities that form a symbiotic relationship with the sponge can amount to as much as 35% of the biomass of its host. The term for this specific symbiotic relationship, where a microbial consortia pairs with a host is called a holobiotic relationship. The sponge as well as the microbial community associated with it will produce a large range of secondary metabolites that help protect it against predators through mechanisms such as chemical defense. The sponge holobiont is an example of the concept of nested ecosystems. Environmental factors act at multiple scales to alter microbiome, holobiont, community, and ecosystem scale processes. Thus, factors that alter microbiome functioning can lead to changes at the holobiont, community, or even ecosystem level and vice versa, illustrating the necessity of considering multiple scales when evaluating functioning in nested ecosystems. Some of these relationships include endosymbionts within bacteriocyte cells, and cyanobacteria or microalgae found below the pinacoderm cell layer where they are able to receive the highest amount of light, used for phototrophy. They can host over 50 different microbial phyla and candidate phyla, including Alphaprotoebacteria, Actinomycetota, Chloroflexota, Nitrospirota, "Cyanobacteria", the taxa Gamma-, the candidate phylum Poribacteria, and Thaumarchaea. Systematics Carl Linnaeus, who classified most kinds of sessile animals as belonging to the order Zoophyta in the class Vermes, mistakenly identified the genus Spongia as plants in the order Algae.[further explanation needed] For a long time thereafter, sponges were assigned to subkingdom Parazoa ("beside the animals") separated from the Eumetazoa which formed the rest of the kingdom Animalia. The phylum Porifera is further divided into classes mainly according to the composition of their skeletons: In the 1970s, sponges with massive calcium carbonate skeletons were assigned to a separate class, Sclerospongiae, otherwise known as "coralline sponges". However, in the 1980s, it was found that these were all members of either the Calcarea or the Demospongiae. So far scientific publications have identified about 9,000 poriferan species, of which about 400 are glass sponges, about 500 are calcareous species, and the rest are demosponges. However, some types of habitat, such as vertical rock and cave walls and galleries in rock and coral boulders, have been investigated very little, even in shallow seas, and may harbor many more species. Sponges were traditionally distributed in three classes: calcareous sponges (Calcarea), glass sponges (Hexactinellida) and demosponges (Demospongiae). However, studies have now shown that the Homoscleromorpha, a group thought to belong to the Demospongiae, has a genetic relationship well separated from other sponge classes.: 153–154 Therefore, they have recently been recognized as the fourth class of sponges. Sponges are divided into classes mainly according to the composition of their skeletons: These are arranged in evolutionary order as shown below in ascending order of their evolution from top to bottom: The phylogeny of sponges has been debated heavily since the advent of phylogenetics. Originally thought to be the sister group to all other animal phyla, there is now considerable evidence that Ctenophora may hold that title instead. Additionally, the monophyly of the phylum is now under question. Several studies have concluded that all other animals emerged from within the sponges, and usually recover that the calcareous sponges and Homoscleromorpha are closer to other animals than to demosponges. The internal relationships of Porifera have proven to be less uncertain. A close relationship of Homoscleromorpha and Calcarea has been recovered in nearly all studies, whether or not they support sponge or eumetazoan monophyly. The position of glass sponges is also fairly certain, with a majority of studies recovering them as the sister of the demosponges. Thus, the uncertainty at the base of the animal family tree is probably best represented by the below cladogram. Hexactinellida Demospongiae Calcarea Homoscleromorpha Ctenophora ParaHoxozoa Evolutionary history Although molecular clocks and biomarkers suggest sponges existed well before the Cambrian explosion of life, silica spicules like those of demosponges are absent from the fossil record until the Cambrian. An unsubstantiated 2002 report exists of spicules in rocks dated around 750 million years ago. Well-preserved fossil sponges from about 580 million years ago in the Ediacaran period have been found in the Doushantuo Formation. These fossils, which include: spicules; pinacocytes; porocytes; archeocytes; sclerocytes; and the internal cavity, have been classified as demosponges. The Ediacaran record of sponges also contains two other genera: the stem-hexactinellid Helicolocellus from the Dengying Formation and the possible stem-archaeocyathan Arimasia from the Nama Group. These genera are both from the "Nama assemblage" of Ediacaran biota, although whether this is due to a genuine lack beforehand or preservational bias is uncertain. Fossils of glass sponges have been found from around 540 million years ago in rocks in Australia, China, and Mongolia. Early Cambrian sponges from Mexico belonging to the genus Kiwetinokia show evidence of fusion of several smaller spicules to form a single large spicule. Calcium carbonate spicules of calcareous sponges have been found in Early Cambrian rocks from about 530 to 523 million years ago in Australia. Other probable demosponges have been found in the Early Cambrian Chengjiang fauna, from 525 to 520 million years ago. Fossils found in the Canadian Northwest Territories dating to 890 million years ago may be sponges; if this finding is confirmed, it suggests the first animals appeared before the Neoproterozoic oxygenation event. Freshwater sponges appear to be much younger, as the earliest known fossils date from the Mid-Eocene period about 48 to 40 million years ago. Although about 90% of modern sponges are demosponges, fossilized remains of this type are less common than those of other types because their skeletons are composed of relatively soft spongin that does not fossilize well. The earliest sponge symbionts are known from the early Silurian. A chemical tracer is 24-isopropyl cholestane, which is a stable derivative of 24-isopropyl cholesterol, which is said to be produced by demosponges but not by eumetazoans ("true animals", i.e. cnidarians and bilaterians). Since choanoflagellates are thought to be animals' closest single-celled relatives, a team of scientists examined the biochemistry and genes of one choanoflagellate species. They concluded that this species could not produce 24-isopropyl cholesterol but that investigation of a wider range of choanoflagellates would be necessary in order to prove that the fossil 24-isopropyl cholestane could only have been produced by demosponges. Although a previous publication reported traces of the chemical 24-isopropyl cholestane in ancient rocks dating to 1,800 million years ago, recent research using a much more accurately dated rock series has revealed that these biomarkers only appear before the end of the Marinoan glaciation approximately 635 million years ago, and that "Biomarker analysis has yet to reveal any convincing evidence for ancient sponges pre-dating the first globally extensive Neoproterozoic glacial episode (the Sturtian, ~713 million years ago in Oman)". While it has been argued that this 'sponge biomarker' could have originated from marine algae, recent research suggests that the algae's ability to produce this biomarker evolved only in the Carboniferous; as such, the biomarker remains strongly supportive of the presence of demosponges in the Cryogenian. Archaeocyathids, which some classify as a type of coralline sponge, are very common fossils in rocks from the Early Cambrian about 530 to 520 million years ago, but apparently died out by the end of the Cambrian 490 million years ago. It has been suggested that they were produced by: sponges; cnidarians; algae; foraminiferans; a completely separate phylum of animals, Archaeocyatha; or even a completely separate kingdom of life, labeled Archaeata or Inferibionta. Since the 1990s, archaeocyathids have been regarded as a distinctive group of sponges. It is difficult to fit chancelloriids into classifications of sponges or more complex animals. An analysis in 1996 concluded that they were closely related to sponges on the grounds that the detailed structure of chancellorid sclerites ("armor plates") is similar to that of fibers of spongin, a collagen protein, in modern keratose (horny) demosponges such as Darwinella. However, another analysis in 2002 concluded that chancelloriids are not sponges and may be intermediate between sponges and more complex animals, among other reasons because their skins were thicker and more tightly connected than those of sponges. In 2008, a detailed analysis of chancelloriids' sclerites concluded that they were very similar to those of halkieriids, mobile bilaterian animals that looked like slugs in chain mail and whose fossils are found in rocks from the very Early Cambrian to the Mid Cambrian. If this is correct, it would create a dilemma, as it is extremely unlikely that totally unrelated organisms could have developed such similar sclerites independently, but the huge difference in the structures of their bodies makes it hard to see how they could be closely related. Fungi Choanoflagellates Glass sponges Demosponges Calcareous sponges Comb jellies Placozoa Cnidaria(jellyfish, etc.) other metazoans Plants Fungi Most demosponges Calcareous sponges Homoscleromorpha Cnidaria(jellyfish, etc.) other metazoans In the 1990s, sponges were widely regarded as a monophyletic group, all of them having descended from a common ancestor that was itself a sponge, and as the "sister-group" to all other metazoans (multi-celled animals), which themselves form a monophyletic group. On the other hand, some 1990s analyses also revived the idea that animals' nearest evolutionary relatives are choanoflagellates, single-celled organisms very similar to sponges' choanocytes – which would imply that most Metazoa evolved from very sponge-like ancestors and therefore that sponges may not be monophyletic, as the same sponge-like ancestors may have given rise both to modern sponges and to non-sponge members of Metazoa. Analyses since 2001 have concluded that Eumetazoa (more complex than sponges) are more closely related to particular groups of sponges than to other sponge groups. Such conclusions imply that sponges are not monophyletic, because the last common ancestor of all sponges would also be a direct ancestor of the Eumetazoa, which are not sponges. A study in 2001 based on comparisons of ribosome DNA concluded that the most fundamental division within sponges was between glass sponges and the rest, and that Eumetazoa are more closely related to calcareous sponges (those with calcium carbonate spicules) than to other types of sponge. In 2007, one analysis based on comparisons of RNA and another based mainly on comparison of spicules concluded that demosponges and glass sponges are more closely related to each other than either is to the calcareous sponges, which in turn are more closely related to Eumetazoa. Other anatomical and biochemical evidence links the Eumetazoa with Homoscleromorpha, a sub-group of demosponges. A comparison in 2007 of nuclear DNA, excluding glass sponges and comb jellies, concluded that: The sperm of Homoscleromorpha share features with the sperm of Eumetazoa, that sperm of other sponges lack. In both Homoscleromorpha and Eumetazoa layers of cells are bound together by attachment to a carpet-like basal membrane composed mainly of "typ IV" collagen, a form of collagen not found in other sponges – although the spongin fibers that reinforce the mesohyl of all demosponges is similar to "type IV" collagen. The analyses described above concluded that sponges are closest to the ancestors of all Metazoa, of all multi-celled animals including both sponges and more complex groups. However, another comparison in 2008 of 150 genes in each of 21 genera, ranging from fungi to humans but including only two species of sponge, suggested that comb jellies (ctenophora) are the sister group to all other lineages of Metazoa included in the sample. If this is correct, either modern comb jellies developed their complex structures independently of other Metazoa, or sponges' ancestors were more complex and all known sponges are drastically simplified forms. The study recommended further analyses using a wider range of sponges and other simple Metazoa such as Placozoa. However, reanalysis of the data showed that the computer algorithms used for analysis were misled by the presence of specific ctenophore genes that were markedly different from those of other species, leaving sponges as either the sister group to all other animals, or an ancestral paraphyletic grade. 'Family trees' constructed using a combination of all available data – morphological, developmental and molecular – concluded that the sponges are in fact a monophyletic group, and with the cnidarians form the sister group to the bilaterians. A very large and internally consistent alignment of 1,719 proteins at the metazoan scale, published in 2017, showed that (i) sponges – represented by Homoscleromorpha, Calcarea, Hexactinellida, and Demospongiae – are monophyletic, (ii) sponges are sister-group to all other multicellular animals, (iii) ctenophores emerge as the second-earliest branching animal lineage, and (iv) placozoans emerge as the third animal lineage, followed by cnidarians sister-group to bilaterians. In March 2021, scientists from Dublin found additional evidence that sponges are the sister group to all other animals, while in May 2023, Schultz et al. found patterns of irreversible change in genome synteny that provide strong evidence that ctenophores are the sister group to all other animals instead. Notable spongiologists Use A report in 1997 described use of sponges as a tool by bottlenose dolphins in Shark Bay in Western Australia. A dolphin will attach a marine sponge to its rostrum, which is presumably then used to protect it when searching for food in the sandy sea bottom. The behavior, known as sponging, has only been observed in this bay and is almost exclusively shown by females. A study in 2005 concluded that mothers teach the behavior to their daughters and that all the sponge users are closely related, suggesting that it is a fairly recent innovation. The calcium carbonate or silica spicules of most sponge genera make them too rough for most uses, but two genera, Hippospongia and Spongia, have soft, entirely fibrous skeletons.: 88 Early Europeans used soft sponges for many purposes, including padding for helmets, portable drinking utensils and municipal water filters. Until the invention of synthetic sponges, they were used as cleaning tools, applicators for paints and ceramic glazes and discreet contraceptives. However, by the mid-20th century, overfishing brought both the animals and the industry close to extinction. Many objects with sponge-like textures are now made of substances not derived from poriferans. Synthetic sponges include personal and household cleaning tools, breast implants, and contraceptive sponges. Typical materials used are cellulose foam, polyurethane foam, and less frequently, silicone foam. The luffa "sponge", also spelled loofah, which is commonly sold for use in the kitchen or the shower, is not derived from an animal but mainly from the fibrous "skeleton" of the sponge gourd (Luffa aegyptiaca, Cucurbitaceae). Sponges have medicinal potential due to the presence in sponges themselves or their microbial symbionts of chemicals that may be used to control viruses, bacteria, tumors and fungi. Lacking any protective shell or means of escape, sponges have evolved to synthesize a variety of unusual compounds. One such class is the oxidized fatty acid derivatives called oxylipins. Members of this family have been found to have anti-cancer, anti-bacterial and anti-fungal properties. One example isolated from the Okinawan Plakortis sponges, plakoridine A, has shown potential as a cytotoxin to murine lymphoma cells. See also References Further reading External links |
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Contents Orion (constellation) Orion is a prominent set of stars visible during winter in the northern celestial hemisphere. It is one of the 88 modern constellations; it was among the 48 constellations listed by the 2nd-century AD/CE astronomer Ptolemy. It is named after a hunter in Greek mythology. Orion is most prominent during winter evenings in the Northern Hemisphere, as are five other constellations that have stars in the Winter Hexagon asterism. Orion's two brightest stars, Rigel (β) and Betelgeuse (α), are both among the brightest stars in the night sky; both are supergiants and slightly variable. There are a further six stars brighter than magnitude 3.0, including three making the short straight line of the Orion's Belt asterism. Orion also hosts the radiant of the annual Orionids, the strongest meteor shower associated with Halley's Comet, and the Orion Nebula, one of the brightest nebulae in the sky. Characteristics Orion is bordered by Taurus to the northwest, Eridanus to the southwest, Lepus to the south, Monoceros to the east, and Gemini to the northeast. Covering 594 square degrees, Orion ranks 26th of the 88 constellations in size. The constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of 26 sides. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 04h 43.3m and 06h 25.5m , while the declination coordinates are between 22.87° and −10.97°. The constellation's three-letter abbreviation, as adopted by the International Astronomical Union in 1922, is "Ori". Orion is most visible in the evening sky from January to April, winter in the Northern Hemisphere, and summer in the Southern Hemisphere. In the tropics (less than about 8° from the equator), the constellation transits at the zenith. From May to July (summer in the Northern Hemisphere, winter in the Southern Hemisphere), Orion is in the daytime sky and thus invisible at most latitudes. However, for much of Antarctica in the Southern Hemisphere's winter months, the Sun is below the horizon even at midday. Stars (and thus Orion, but only the brightest stars) are then visible at twilight for a few hours around local noon, just in the brightest section of the sky low in the North where the Sun is just below the horizon. At the same time of day at the South Pole itself (Amundsen–Scott South Pole Station), Rigel is only 8° above the horizon, and the Belt sweeps just along it. In the Southern Hemisphere's summer months, when Orion is normally visible in the night sky, the constellation is actually not visible in Antarctica because the Sun does not set at that time of year south of the Antarctic Circle. In countries close to the equator (e.g. Kenya, Indonesia, Colombia, Ecuador), Orion appears overhead in December around midnight and in the February evening sky. Navigational aid Orion is very useful as an aid to locating other stars. By extending the line of the Belt southeastward, Sirius (α CMa) can be found; northwestward, Aldebaran (α Tau). A line eastward across the two shoulders indicates the direction of Procyon (α CMi). A line from Rigel through Betelgeuse points to Castor and Pollux (α Gem and β Gem). Additionally, Rigel is part of the Winter Circle asterism. Sirius and Procyon, which may be located from Orion by following imaginary lines (see map), also are points in both the Winter Triangle and the Circle. Features Orion's seven brightest stars form a distinctive hourglass-shaped asterism, or pattern, in the night sky. Four stars—Rigel, Betelgeuse, Bellatrix, and Saiph—form a large roughly rectangular shape, at the center of which lie the three stars of Orion's Belt—Alnitak, Alnilam, and Mintaka. His head is marked by an additional eighth star called Meissa, which is fairly bright to the observer. Descending from the Belt is a smaller line of three stars, Orion's Sword (the middle of which is in fact not a star but the Orion Nebula), also known as the hunter's sword. Many of the stars are luminous hot blue supergiants, with the stars of the Belt and Sword forming the Orion OB1 association. Standing out by its red hue, Betelgeuse may nevertheless be a runaway member of the same group. Orion's Belt, or The Belt of Orion, is an asterism within the constellation. It consists of three bright stars: Alnitak (Zeta Orionis), Alnilam (Epsilon Orionis), and Mintaka (Delta Orionis). Alnitak is around 800 light-years away from Earth, 100,000 times more luminous than the Sun, and shines with a magnitude of 1.8; much of its radiation is in the ultraviolet range, which the human eye cannot see. Alnilam is approximately 2,000 light-years from Earth, shines with a magnitude of 1.70, and with an ultraviolet light that is 375,000 times more luminous than the Sun. Mintaka is 915 light-years away and shines with a magnitude of 2.21. It is 90,000 times more luminous than the Sun and is a double star: the two orbit each other every 5.73 days. In the Northern Hemisphere, Orion's Belt is best visible in the night sky during the month of January at around 9:00 pm, when it is approximately around the local meridian. Just southwest of Alnitak lies Sigma Orionis, a multiple star system composed of five stars that have a combined apparent magnitude of 3.7 and lying at a distance of 1150 light-years. Southwest of Mintaka lies the quadruple star Eta Orionis. Orion's Sword contains the Orion Nebula, the Messier 43 nebula, Sh 2-279 (also known as the Running Man Nebula), and the stars Theta Orionis, Iota Orionis, and 42 Orionis. Three stars comprise a small triangle that marks the head. The apex is marked by Meissa (Lambda Orionis), a hot blue giant of spectral type O8 III and apparent magnitude 3.54, which lies some 1100 light-years distant. Phi-1 and Phi-2 Orionis make up the base. Also nearby is the young star FU Orionis. Stretching north from Betelgeuse are the stars that make up Orion's club. Mu Orionis marks the elbow, Nu and Xi mark the handle of the club, and Chi1 and Chi2 mark the end of the club. Just east of Chi1 is the Mira-type variable red giant star U Orionis. West from Bellatrix lie six stars all designated Pi Orionis (π1 Ori, π2 Ori, π3 Ori, π4 Ori, π5 Ori, and π6 Ori) which make up Orion's shield. Around 20 October each year, the Orionid meteor shower (Orionids) reaches its peak. Coming from the border with the constellation Gemini, as many as 20 meteors per hour can be seen. The shower's parent body is Halley's Comet. Hanging from Orion's Belt is his sword, consisting of the multiple stars θ1 and θ2 Orionis, called the Trapezium and the Orion Nebula (M42). This is a spectacular object that can be clearly identified with the naked eye as something other than a star. Using binoculars, its clouds of nascent stars, luminous gas, and dust can be observed. The Trapezium cluster has many newborn stars, including several brown dwarfs, all of which are at an approximate distance of 1,500 light-years. Named for the four bright stars that form a trapezoid, it is largely illuminated by the brightest stars, which are only a few hundred thousand years old. Observations by the Chandra X-ray Observatory show both the extreme temperatures of the main stars—up to 60,000 kelvins—and the star forming regions still extant in the surrounding nebula. M78 (NGC 2068) is a nebula in Orion. With an overall magnitude of 8.0, it is significantly dimmer than the Great Orion Nebula that lies to its south; however, it is at approximately the same distance, at 1600 light-years from Earth. It can easily be mistaken for a comet in the eyepiece of a telescope. M78 is associated with the variable star V351 Orionis, whose magnitude changes are visible in very short periods of time. Another fairly bright nebula in Orion is NGC 1999, also close to the Great Orion Nebula. It has an integrated magnitude of 10.5 and is 1500 light-years from Earth. The variable star V380 Orionis is embedded in NGC 1999. Another famous nebula is IC 434, the Horsehead Nebula, near Alnitak (Zeta Orionis). It contains a dark dust cloud whose shape gives the nebula its name. NGC 2174 is an emission nebula located 6400 light-years from Earth. Besides these nebulae, surveying Orion with a small telescope will reveal a wealth of interesting deep-sky objects, including M43, M78, and multiple stars including Iota Orionis and Sigma Orionis. A larger telescope may reveal objects such as the Flame Nebula (NGC 2024), as well as fainter and tighter multiple stars and nebulae. Barnard's Loop can be seen on very dark nights or using long-exposure photography. All of these nebulae are part of the larger Orion molecular cloud complex, which is located approximately 1,500 light-years away and is hundreds of light-years across. Due to its proximity, it is one of the most intense regions of stellar formation visible from Earth. The Orion molecular cloud complex forms the eastern part of an even larger structure, the Orion–Eridanus Superbubble, which is visible in X-rays and in hydrogen emissions. History and mythology The distinctive pattern of Orion is recognized in numerous cultures around the world, and many myths are associated with it. Orion is used as a symbol in the modern world. In Siberia, the Chukchi people see Orion as a hunter; an arrow he has shot is represented by Aldebaran (Alpha Tauri), with the same figure as other Western depictions. In Greek mythology, Orion was a gigantic, supernaturally strong hunter, born to Euryale, a Gorgon, and Poseidon (Neptune), god of the sea. One myth recounts Gaia's rage at Orion, who dared to say that he would kill every animal on Earth. The angry goddess tried to dispatch Orion with a scorpion. This is given as the reason that the constellations of Scorpius and Orion are never in the sky at the same time. However, Ophiuchus, the Serpent Bearer, revived Orion with an antidote. This is said to be the reason that the constellation of Ophiuchus stands midway between the Scorpion and the Hunter in the sky. The constellation is mentioned in Horace's Odes (Ode 3.27.18), Homer's Odyssey (Book 5, line 283) and Iliad, and Virgil's Aeneid (Book 1, line 535). In old Hungarian tradition, Orion is known as "Archer" (Íjász), or "Reaper" (Kaszás). In recently rediscovered myths, he is called Nimrod (Hungarian: Nimród), the greatest hunter, father of the twins Hunor and Magor. The π and o stars (on upper right) form together the reflex bow or the lifted scythe. In other Hungarian traditions, Orion's Belt is known as "Judge's stick" (Bírópálca). In Ireland and Scotland, Orion was called An Bodach, a figure from Irish folklore whose name literally means "the one with a penis [bod]" and was the husband of the Cailleach (hag). In Scandinavian tradition, Orion's Belt was known as "Frigg's Distaff" (friggerock) or "Freyja's distaff". The Finns call Orion's Belt and the stars below it "Väinämöinen's scythe" (Väinämöisen viikate). Another name for the asterism of Alnilam, Alnitak, and Mintaka is "Väinämöinen's Belt" (Väinämöisen vyö) and the stars "hanging" from the Belt as "Kaleva's sword" (Kalevanmiekka). There are claims in popular media that the Adorant from the Geißenklösterle cave, an ivory carving estimated to be 35,000 to 40,000 years old, is the first known depiction of the constellation. Scholars dismiss such interpretations, saying that perceived details such as a belt and sword derive from preexisting features in the grain structure of the ivory. The Babylonian star catalogues of the Late Bronze Age name Orion MULSIPA.ZI.AN.NA,[note 1] "The Heavenly Shepherd" or "True Shepherd of Anu" – Anu being the chief god of the heavenly realms. The Babylonian constellation is sacred to Papshukal and Ninshubur, both minor gods fulfilling the role of "messenger to the gods". Papshukal is closely associated with the figure of a walking bird on Babylonian boundary stones, and on the star map the figure of the Rooster is located below and behind the figure of the True Shepherd—both constellations represent the herald of the gods, in his bird and human forms respectively. In ancient Egypt, the stars of Orion were regarded as a god, called Sah. Because Orion rises before Sirius, the star whose heliacal rising was the basis for the Solar Egyptian calendar, Sah was closely linked with Sopdet, the goddess who personified Sirius. The god Sopdu is said to be the son of Sah and Sopdet. Sah is syncretized with Osiris, while Sopdet is syncretized with Osiris' mythological wife, Isis. In the Pyramid Texts, from the 24th and 23rd centuries BC, Sah is one of many gods whose form the dead pharaoh is said to take in the afterlife. The Armenians identified their legendary patriarch and founder Hayk with Orion. Hayk is also the name of the Orion constellation in the Armenian translation of the Bible. The Bible mentions Orion three times, naming it "Kesil" (כסיל, literally – fool). Though, this name perhaps is etymologically connected with "Kislev", the name for the ninth month of the Hebrew calendar (i.e. November–December), which, in turn, may derive from the Hebrew root K-S-L as in the words "kesel, kisla" (כֵּסֶל, כִּסְלָה, hope, positiveness), i.e. hope for winter rains.: Job 9:9 ("He is the maker of the Bear and Orion"), Job 38:31 ("Can you loosen Orion's belt?"), and Amos 5:8 ("He who made the Pleiades and Orion"). In ancient Aram, the constellation was known as Nephîlā′, the Nephilim are said to be Orion's descendants. In medieval Muslim astronomy, Orion was known as al-jabbar, "the giant". Orion's sixth brightest star, Saiph, is named from the Arabic, saif al-jabbar, meaning "sword of the giant". In China, Orion was one of the 28 lunar mansions Sieu (Xiù) (宿). It is known as Shen (參), literally meaning "three", for the stars of Orion's Belt. The Chinese character 參 (pinyin shēn) originally meant the constellation Orion (Chinese: 參宿; pinyin: shēnxiù); its Shang dynasty version, over three millennia old, contains at the top a representation of the three stars of Orion's Belt atop a man's head (the bottom portion representing the sound of the word was added later). The Rigveda refers to the constellation as Mriga (the Deer). Nataraja, "the cosmic dancer", is often interpreted as the representation of Orion. Rudra, the Rigvedic form of Shiva, is the presiding deity of Ardra nakshatra (Betelgeuse) of Hindu astrology. The Jain Symbol carved in the Udayagiri and Khandagiri Caves, India in 1st century BCE has a striking resemblance with Orion. Bugis sailors identified the three stars in Orion's Belt as tanra tellué, meaning "sign of three". The Seri people of northwestern Mexico call the three stars in Orion's Belt Hapj (a name denoting a hunter) which consists of three stars: Hap (mule deer), Haamoja (pronghorn), and Mojet (bighorn sheep). Hap is in the middle and has been shot by the hunter; its blood has dripped onto Tiburón Island. The same three stars are known in Spain and most of Latin America as "Las tres Marías" (Spanish for "The Three Marys"). In Puerto Rico, the three stars are known as the "Los Tres Reyes Magos" (Spanish for The Three Wise Men). The Ojibwa/Chippewa Native Americans call this constellation Mesabi for Big Man. To the Lakota Native Americans, Tayamnicankhu (Orion's Belt) is the spine of a bison. The great rectangle of Orion is the bison's ribs; the Pleiades star cluster in nearby Taurus is the bison's head; and Sirius in Canis Major, known as Tayamnisinte, is its tail. Another Lakota myth mentions that the bottom half of Orion, the Constellation of the Hand, represented the arm of a chief that was ripped off by the Thunder People as a punishment from the gods for his selfishness. His daughter offered to marry the person who can retrieve his arm from the sky, so the young warrior Fallen Star (whose father was a star and whose mother was human) returned his arm and married his daughter, symbolizing harmony between the gods and humanity with the help of the younger generation. The index finger is represented by Rigel; the Orion Nebula is the thumb; the Belt of Orion is the wrist; and the star Beta Eridani is the pinky finger. The seven primary stars of Orion make up the Polynesian constellation Heiheionakeiki which represents a child's string figure similar to a cat's cradle. Several precolonial Filipinos referred to the belt region in particular as "balatik" (ballista) as it resembles a trap of the same name which fires arrows by itself and is usually used for catching pigs from the bush. Spanish colonization later led to some ethnic groups referring to Orion's Belt as "Tres Marias" or "Tatlong Maria." In Māori tradition, the star Rigel (known as Puanga or Puaka) is closely connected with the celebration of Matariki. The rising of Matariki (the Pleiades) and Rigel before sunrise in midwinter marks the start of the Māori year. In Javanese culture, the constellation is often called Lintang Waluku or Bintang Bajak, referring to the shape of a paddy field plow. The imagery of the Belt and Sword has found its way into popular Western culture, for example in the form of the shoulder insignia of the 27th Infantry Division of the United States Army during both World Wars, probably owing to a pun on the name of the division's first commander, Major General John F. O'Ryan. The film distribution company Orion Pictures used the constellation as its logo. In artistic renderings, the surrounding constellations are sometimes related to Orion: he is depicted standing next to the river Eridanus with his two hunting dogs Canis Major and Canis Minor, fighting Taurus. He is sometimes depicted hunting Lepus the hare. He sometimes is depicted to have a lion's hide in his hand. There are alternative ways to visualise Orion. From the Southern Hemisphere, Orion is oriented south-upward, and the Belt and Sword are sometimes called the saucepan or pot in Australia and New Zealand. Orion's Belt is called Drie Konings (Three Kings) or the Drie Susters (Three Sisters) by Afrikaans speakers in South Africa and are referred to as les Trois Rois (the Three Kings) in Daudet's Lettres de Mon Moulin (1866). The appellation Driekoningen (the Three Kings) is also often found in 17th and 18th-century Dutch star charts and seaman's guides. The same three stars are known in Spain, Latin America, and the Philippines as "Las Tres Marías" (The Three Marys), and as "Los Tres Reyes Magos" (The Three Wise Men) in Puerto Rico. Even traditional depictions of Orion have varied greatly. Cicero drew Orion in a similar fashion to the modern depiction. The Hunter held an unidentified animal skin aloft in his right hand; his hand was represented by Omicron2 Orionis and the skin was represented by the five stars designated Pi Orionis. Saiph and Rigel represented his left and right knees, while Eta Orionis and Lambda Leporis were his left and right feet, respectively. As in the modern depiction, Mintaka, Alnilam, and Alnitak represented his Belt. His left shoulder was represented by Betelgeuse, and Mu Orionis made up his left arm. Meissa was his head, and Bellatrix his right shoulder. The depiction of Hyginus was similar to that of Cicero, though the two differed in a few important areas. Cicero's animal skin became Hyginus's shield (Omicron and Pi Orionis), and instead of an arm marked out by Mu Orionis, he holds a club (Chi Orionis). His right leg is represented by Theta Orionis and his left leg is represented by Lambda, Mu, and Epsilon Leporis. Further Western European and Arabic depictions have followed these two models. Future Orion is located on the celestial equator, but it will not always be so located due to the effects of precession of the Earth's axis. Orion lies well south of the ecliptic, and it only happens to lie on the celestial equator because the point on the ecliptic that corresponds to the June solstice is close to the border of Gemini and Taurus, to the north of Orion. Precession will eventually carry Orion further south, and by AD 14000, Orion will be far enough south that it will no longer be visible from the latitude of Great Britain. Further in the future, Orion's stars will gradually move away from the constellation due to proper motion. However, Orion's brightest stars all lie at a large distance from Earth on an astronomical scale—much farther away than Sirius, for example. Orion will still be recognizable long after most of the other constellations—composed of relatively nearby stars—have distorted into new configurations, with the exception of a few of its stars eventually exploding as supernovae, for example Betelgeuse, which is predicted to explode sometime in the next million years. See also References External links |
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[SOURCE: https://en.wikipedia.org/wiki/History_of_the_ancient_Levant] | [TOKENS: 7387] |
Contents History of the ancient Levant The Levant is the area in Southwest Asia, south of the Taurus Mountains, bounded by the Mediterranean Sea in the west, the Arabian Desert in the south, and Mesopotamia in the east. It stretches roughly 400 mi (640 km) north to south, from the Taurus Mountains to the Sinai Peninsula and Syrian Desert, and east to west between the Mediterranean Sea and the Khabur river. The term is often used to refer to the following regions or modern states: Syria, Lebanon, Israel, Palestine, Jordan and Hatay Province in Turkey. More broadly it also includes: Sinai (Egypt), Cilicia (Turkey) and Cyprus. The Levant is one of the earliest centers of sedentism and agriculture in history, and some of the earliest agrarian cultures, Pre-Pottery Neolithic, developed in the region. Previously regarded as a peripheral region in the ancient Near East, modern academia largely considers the Levant as a center of civilization on its own, independent of Mesopotamia and Egypt. Throughout the Bronze and Iron ages, the Levant was home to many ancient Semitic-speaking peoples and kingdoms, and is considered by many to be the urheimat of Semitic languages. Stone Age Anatomically modern Homo sapiens are demonstrated at the area of Mount Carmel in Canaan during the Middle Paleolithic dating from c. 90,000 BC. These migrants out of Africa seem to have been unsuccessful, and by c. 60,000 BC in the Levant, Neanderthal groups seem to have benefited from the worsening climate and replaced Homo sapiens, who were possibly confined once more to Africa. A second move out of Africa is demonstrated by the Boker Tachtit Upper Paleolithic culture, from 52,000 to 50,000 BC, with humans at Ksar Akil XXV level being modern humans. This culture bears close resemblance to the Badoshan Aurignacian culture of Iran, and the later Sebilian I Egyptian culture of c. 50,000 BC. Stephen Oppenheimer suggests that this reflects a movement of modern human groups back into North Africa, at this time. It would appear this sets the date by which Homo sapiens Upper Paleolithic cultures begin replacing Neanderthal Levalo-Mousterian, and by c. 40,000 BC the region was occupied by the Levanto-Aurignacian Ahmarian culture, lasting from 39,000 to 24,000 BC. This culture was quite successful spreading as the Antelian culture (late Aurignacian), as far as Southern Anatolia, with the Atlitan culture. After the Late Glacial Maxima, a new Epipaleolithic culture appears. The appearance of the Kebaran culture, of microlithic type implies a significant rupture in the cultural continuity of Levantine Upper Paleolithic. The Kebaran culture, with its use of microliths, is associated with the use of the bow and arrow and the domestication of the dog. Extending from 18,000 to 10,500 BC, the Kebaran culture shows clear connections to the earlier microlithic cultures using the bow and arrow, and using grinding stones to harvest wild grains, that developed from the c. 24,000 – c. 17,000 BC Halfan culture of Egypt, that came from the still earlier Aterian tradition of the Sahara. Some linguists see this as the earliest arrival of Nostratic languages in the Middle East. Kebaran culture was quite successful, and was ancestral to the later Natufian culture (12,500–9,500 BC), which extended throughout the whole of the Levantine region. These people pioneered the first sedentary settlements, and may have supported themselves from fishing and the harvest of wild grains plentiful in the region at that time. As of July 2018,[update] the oldest remains of bread were discovered c. 12,400 BC at the archaeological site of Shubayqa 1, once home of the Natufian hunter-gatherers, roughly 4,000 years before the advent of agriculture. Natufian culture also demonstrates the earliest domestication of the dog, and the assistance of this animal in hunting and guarding human settlements may have contributed to the successful spread of this culture. In the northern Syrian, eastern Anatolian region of the Levant, Natufian culture at Cayonu and Mureybet developed the first fully agricultural culture with the addition of wild grains, later being supplemented with domesticated sheep and goats, which were probably domesticated first by the Zarzian culture of Northern Iraq and Iran (which like the Natufian culture may have also developed from Kebaran). By 8500–7500 BC, the Pre-Pottery Neolithic A (PPNA) culture developed out of the earlier local tradition of Natufian, dwelling in round houses, and building the first defensive site at Tell es-Sultan (ancient Jericho) (guarding a valuable fresh water spring). This was replaced in 7500 BC by Pre-Pottery Neolithic B (PPNB), dwelling in square houses, coming from Northern Syria and the Euphrates bend. During the period of 8500–7500 BC, another hunter-gatherer group, showing clear affinities with the cultures of Egypt (particularly the Outacha retouch technique for working stone) was in Sinai. This Harifian culture may have adopted the use of pottery from the Isnan culture and Helwan culture of Egypt [citation needed] (which lasted from 9000 to 4500 BC), and subsequently fused with elements from the PPNB culture during the climatic crisis of 6000 BC to form what Juris Zarins calls the Syro-Arabian pastoral technocomplex, which saw the spread of the first Nomadic pastoralists in the Ancient Near East. These extended southwards along the Red Sea coast and penetrating the Arabian bifacial cultures, which became progressively more Neolithic and pastoral, and extending north and eastwards, to lay the foundations for the tent-dwelling Martu and Akkadian peoples of Mesopotamia. In the Amuq valley of Syria, PPNB culture seems to have survived, influencing further cultural developments further south. Nomadic elements fused with PPNB to form the Minhata Culture and Yarmukian Culture, which were to spread southwards, beginning the development of the classic mixed farming Mediterranean culture, and from 5600 BC were associated with the Ghassulian culture of the region, the first Chalcolithic culture of the Levant. This period[which?] also witnessed the development of megalithic structures, which continued into the Bronze Age.[dubious – discuss] Historically, the Bedouin engaged in nomadic herding, agriculture and sometimes fishing in the Syrian steppe since 6000 BC. By about 850 BC, a complex network of settlements and camps were established. The earliest Arab tribes emerged from Bedouins. Copper Age The Kish civilization or Kish tradition is a concept created by Ignace Gelb and discarded by more recent scholarship, which Gelb placed in what he called the early East Semitic era in Mesopotamia and the Levant, starting in the early 4th millennium BC. The concept encompassed the sites of Ebla and Mari in the Levant, Nagar in the north, and the proto-Akkadian sites of Abu Salabikh and Kish in central Mesopotamia, which constituted the Uri region as it was known to the Sumerians. The Kish civilisation was considered to end with the rise of the Akkadian empire in the 24th century BC. Bronze Age Some recent scholars dealing with the Syrian part of the Levant during the Bronze Age use Syria-specific subdivision: "Early/Proto Syrian" for the Early Bronze Age (3300–2000 BC); "Old Syrian" for the Middle Bronze Age (2000–1550 BC); and "Middle Syrian" for the Late Bronze Age (1550–1200 BC). "Neo-Syrian" corresponds to the Early Iron Age. The Early Syrian period was dominated by the East Semitic-speaking kingdoms of Ebla, Nagar and the Mari. At its greatest extent, Ebla controlled an area roughly half the size of modern Syria, from Ursa'um in the north, to the area around Damascus in the south, and from Phoenicia and the coastal mountains in the west, to Haddu in the east, with more than sixty vassal kingdoms and city-states. Mobile nomadic tribal confederations such as Mardu, Dadanu and Ib'al lived in the steppes to the south of Ebla. Ebla and Mari were incorporated into the Akkadian Empire by Sargon of Akkad and his successors, until the empire collapsed due to a major climatic event around 2200 BC. This event prompted the influx of nomadic Amorites into Sumer, and correlates with a subsequent influx and settlement expansion in many regions of Syria as well. In the later periods of the Third Dynasty of Ur, immigrating Amorites had become such a force that the king of Ur, Shu-Sin, constructed a 270-kilometre (170 mi) wall dubbed "Repeller of the Amorites", extending in between the Tigris and Euphrates, to hold them off. The Amorites are depicted in contemporary records as nomadic tribes under chiefs, who forced themselves into lands they needed to graze their herds. Some of the Akkadian literature of this era speaks disparagingly of the Amorites and implies that the urbanized people of Mesopotamia viewed their nomadic and primitive way of life with disgust and contempt. In the Sumerian myth "Marriage of Martu", written early in the 2nd millennium BC, a goddess considering marriage to the god of the Amorites is warned: Now listen, their hands are destructive and their features are those of monkeys; (An Amorite) is one who eats what (the Moon-god) Nanna forbids and does not show reverence. They never stop roaming about [...], they are an abomination to the gods' dwellings. Their ideas are confused; they cause only disturbance. (The Amorite) is clothed in sack-leather [...], lives in a tent, exposed to wind and rain, and cannot properly recite prayers. He lives in the mountains and ignores the places of gods, digs up truffles in the foothills, does not know how to bend the knee (in prayer), and eats raw flesh. He has no house during his life, and when he dies he will not be carried to a burial-place. My girlfriend, why would you marry Martu? The Amorites came to politically and culturally dominate much of the ancient Near East for centuries, and founded multiple kingdoms throughout the region including the Old Babylonian Empire. Famed Amorites included Babylonian king Hammurabi and warlord Shamshi-Adad I. After the decline of the Third dynasty of Ur, Amorite rulers gained power in a number of Mesopotamian city-states beginning in the Isin-Larsa period and peaking in the Old Babylonian period. In southern Mesopotamia, Babylon became the major power under Amorite ruler Sumu-la-El and his successor Hammurabi (c. 1792–1750 BC). In northern Mesopotamia, the Amorite warlord Shamshi-Adad I conquered much of Assyria and formed the large, though short-lived Kingdom of Upper Mesoptamia. In the Levant, Amorite dynasties ruled various kingdoms of Qatna, Ebla and Yamhad, which also had a significant Hurrian population. Mari was similarly ruled by the Amorite Lim dynasty which belonged to the pastoral Amorites known as the Haneans, who were split into the Yaminites (sons of the south) and Sim'alites (sons of the north) tribes. Another Semitic peoples during this period, the Suteans, inhabited Suhum and were in direct conflict with Mari. The Suteans were nomads famous in epic poetry for being fierce nomadic warriors, and like the Habiru, traditionally worked as mercenaries. Amorite elements were also to be found in Egypt with the Fourteenth Dynasty of Egypt of the Nile Delta, whose rulers bore distinctly Amorite names such as Yakbim. The Hyksos, who overran Egypt and founded the Fifteenth dynasty, were an amalgam of Levantine elements including the Amorites. By the 16th and 15th centuries BC, most of the major urban centers in the Levant had been overrun and went into steep decline. Mari was destroyed and reduced in a series of wars and conflicts with Babylon, while Yamhad and Ebla were conquered and completely destroyed by Hittite king Mursili I in about 1600 BC. In northern Mesopotamia, the era ended with the defeat of the Amorite states by Assyrian kings Puzur-Sin and Adasi between in 1740–1735 BC, and the rise of the native Sealand Dynasty further south. In Egypt, Ahmose I expelled the Levantine Hyksos rulers from power, pushing Egypt's borders further into Canaan. The Amorites were eventually absorbed by another West Semitic-speaking people known collectively as the Ahlamu. The Arameans rose to be the prominent group amongst the Ahlamu, and from c. 1200 BC on, the Amorites disappeared from the pages of history. Between 1550–1170 BC, much of the Levant was contested between Egypt and the Hittites. The political vacuum paved way for the rise of Mitanni, a mixed Semitic and Hurrian-speaking kingdom whose names of the ruling family bore influence from Indo-Aryan languages. Egyptian rule remained strong over the Canaanite-city states in Palestine, facing resistance mainly from pastoral nomadic groups such as the Shasu. The Shasu grew so powerful that they were able to cut off Egypt's northern routes through Palestine and Transjordan, prompting a vigorous punitive campaigns by Ramesses II and his son Merneptah. After Egyptians abandoned the region, Canaanite city-states came under the mercy of the Shasu and the Habiru, who were seen as 'mighty enemies'. Egyptian control over the southern Levant completely collapsed in the wake of the Late Bronze Age collapse. Between c. 1200–1150 BC, all of these powers suddenly collapsed. Centralized state systems collapsed, and the region was hit by famine. Chaos ensued throughout the region, and many urban centers were burnt to the ground by famine-struck natives and an assortment of raiders known as the Sea Peoples, who eventually settled in the Levant. The Sea Peoples' origins are ambiguous and many theories have proposed them to be Trojans, Sardinians, Achaeans, Sicilians or Lycians. Urban centers which survived Hittite and Egyptian expansions in 1600 BC, including Alalakh, Ugarit, Megiddo and Kadesh, were razed to the ground and were never rebuilt. The Hittite empire was destroyed, and its capital Tarḫuntašša was razed to the ground. Egypt repelled its attackers with only a major effort, and over the next century shrank to its territorial core, its central authority permanently weakened. Iron Age Despite the tumultuous beginning of the Iron Age, the period a number of technological innovations spread, most notably iron working and the Phoenician alphabet, which was developed by the Phoenicians around the 11th century BC from the Old Canaanite script, possibly a hybrid of Hieroglyphs, Cuneiform and the mysterious Byblos syllabary. The massive destruction at the end of the Bronze Age collapsed most major polities and city-states of the Bronze Age. The early Iron Age in Syria and Mesopotamia saw a dispersal of settlements and ruralization, with the appearance of large numbers of hamlets, villages, and farmsteads. Following the Late Bronze age collapse, Aramean tribes and kingdoms came to dominate most of present-day Syria and Upper Mesopotamia. The pastoral expansion of the Arameans in upper Mesopotamia quickly brought them into conflict with the Assyrians, whose dominion in upper Mesopotamia consequently came to an end (ca. 1114–1056 BC). Aramean infiltration also extended into southern Mesopotamia, where their presence was felt by cities in central Babylonia as early as the 10th century. Some of the major Aramaean kingdoms included Aram-Damascus, Hamath, Samʾal and Aram-Zobah (in Syria); and Bet-Adini, Bet-Bagyan, Bet-Zamani and Bet-Halupe (in upper Mesopotamia). In northern Syria, the dispersal of the Hittites and expansion of Aramaeans gave rise to a conglomeration of West Semitic and Anatolian-speaking kingdoms known as the Neo-Hittite states. The Chaldeans, another West Semitic-speaking group from the Levant, infiltrated Babylonia after the Aramaeans (ca. 940–860 BC), where they were actively involved in rebellion against the Assyrians. Assyrian texts of the 9th century BC further mention the Arabs (Aribi), who inhabited swaths of land in the Levant and in Babylonian border region in a similar suit to the Aramaeans, their presence seemingly intermingled. In Laqe near Terqa, a mix of Arab and Aramaean tribes settled the lower Khabur valley in 12th century BC, forming a confederation comparable to other tribal leagues of the time. Along the coast of northern Canaan, the Phoenician city-states managed to escape the destruction that ensued in the Late Bronze Age collapse and developed into commercial maritime powers with established colonies across the Mediterranean Sea. These colonies stretched into Sardinia, North Africa, Cyprus, Sicily, Malta and Iberia. One prominent colony, Carthage (from Punic qrt-ḥdšt, meaning 'New City'), would eventually become an independent city-state which quarrelled with the Roman Republic over control of the Mediterranean. The Phoenicians transmitted their alphabetic system across the maritime networks, which was eventually adopted and developed into Greek alphabet and Latin alphabet. In the southern Levant, pastoral nomadic tribal groups began to settle down at the start of the 11th century. These included the Israelites in the Cisjordan and the Ammonites, Moabites and Edomites in the Transjordan. The Philistines, a group of Aegean immigrants arrived at the shores of Canaan circa 1175 BC and settled there. During the seventh century BC, no fewer than eight nations were settled in the southern Levant. These included the Arameans of the kingdom of Geshur; the Samaritans who replaced the Israelite kingdom in Samaria; the Phoenicians in the northern cities and parts of Galilee; the Philistines in the Philistine pentapolis; the three kingdoms of the Transjordan– Ammon, Moab and Edom; and the Judaeans of Kingdom of Judah. In the Iron Age, the Levant was characterized by patches of scattered kingdoms and tribal confederations which originated from the same cultural and linguistic milieu. Occasionally, these peoples united against expansion from neighboring regions, notably in the Battle of Qarqar (853 BC) which saw an alliance of Aramaeans, Phoenicians, Israelites, Ammonites and Arabs united against the Assyrians under Shalmaneser III (859–824 BC). The alliance, led by Hadadezer of Aram-Damascus, succeeded in halting the Assyrian army boasting 120,000 soldiers active in Syria. By 843 BC the political situation in central and southern Syria changed radically, after Hazael succeeded Hadadezer as king of Aram-Damascus. The anti-Assyrian alliance dissolved, and former allies of Aram-Damascus turned into enemies. In 842, Hazael invaded the northern parts of the Kingdom of Israel and reportedly penetrated into the coastal planes as far as Asdod, seizing Gilead and eastern Jordan in the process. Hazael survived Assyrian attempts to subjugate Aram-Damascus and also expanded his influence in northern Syria, where he reportedly crossed the Orontes river and seized territories as far as Aleppo. These northern forays allowed Hazael to control much of Syria and Palestine, from Egypt to the Euphrates. Hazael's power far exceeded that of former Aramean kings, and some scholars consider his state to have been a nascent empire. The Assyrians managed to subdue the Levantine states after multiple campaigns that were finalized by Tiglath-Pileser III (745–727 BC). Consolidation of Assyrian rule was followed by numerous revolts throughout the Levant, including division along pro- and anti-Assyrian axes, and intra-Levantine conflict in the Syro-Ephraimite War. The anti-Assyrian axis included Damascus–Tyre–Samaria–the Arabs; and a pro-Assyrian axis which included Arwad, Ashqalon and Gaza joined by Judah, Ammon, Moab and Edom. The anti-Assyrian forces were eventually crushed by 732 BC. Aram-Damascus was annexed and its population was deported; Hamath was razed to the ground and Arameans were prohibited from rebuilding it; the Kingdom of Israel based in Samaria was destroyed and, according to Biblical accounts, the city's population was deported into Assyrian captivity. The fierce resistance and fighting capabilities of the Arameans convinced the Assyrian kings to incorporate them into the army, namely the tribes of Gurru and Itu'u. By the time of Shalmaneser V (727–722 BC), these tribes were an essential part of the empire, and were given the task of securing the empire's peripheries. The Aramaean identity of these tribes probably contributed to the consolidation of Aramaic's prestigious status as the empire's lingua franca. After the Battle of Carchemish, which effectively annihilated Assyrian resistance and Egyptian intervention, Nebuchadnezzar II besieged Jerusalem and destroyed the Temple (597 BC), starting the period of the Babylonian captivity, which lasted about half a century. Nebuchadnezzar also besieged the Phoenician city of Tyre for 13 years (586–573 BC). The subsequent balance of power was, however, short-lived. In the 550s BC, the Achaemenids revolted against the Medes and gained control of their empire, and over the next few decades annexed the realms of Lydia, Damascus, Babylonia, and Egypt into their empire, consolidating control as far as India. This vast kingdom was divided up into various satrapies and governed roughly according to the Assyrian model, but with a far lighter hand. Babylon became one the empire's four capitals, and the lingua franca was Aramaic. Around this time Zoroastrianism became the predominant religion in Persia. Classical Age Achaemenid Empire took over the Levant after 539 BC, but by the 4th century the Achaemenids had fallen into decline. The Phoenicians frequently rebelled against the Persians, who taxed them heavily, in contrast to the Judeans who were granted return from the exile by Cyrus the Great. The campaigns of Xenophon in 401-399 BC illustrated how very vulnerable Persia had become to armies organized along Greek lines. Eventually, such an army under Alexander the Great conquered the Levant in 333-332 BC. However, Alexander did not live long enough to consolidate his realm, and soon after his death in 323 BC, the greater share of the east eventually went to the descendants of Seleucus I Nicator. Seleucus built his capital Seleucia in 305 BC, but the capital was later moved to Antioch in 240 BC. Alexander and his Seleucid successors founded many poleis in Syria, which were then populated by settled troops and locals. The Seleucids also sponsored Greek settlement from Macedon, Athens, Euboea, Thessaly, Crete and Aetolia in military settlements across northern Syria and Anatolia. It was among these communities that Koine Greek formed and became the standard Greek dialect across the Hellenistic world and the Byzantine empire later on. Use of Koine Greek was largely confined to administration and trade while Aramaic remained the lingua franca in much of the rural areas, whereas Hellenistic urban centers were for the most part bilingual. During the period, Hellenistic culture developed as a fusion of ancient Greek culture and local cultures of Syria, Babylonia and Egypt. The Seleucid kings would also adopt the title 'Basileus (King) of Syria'. Hellenistic settlements established by Alexander and his Seleucid successors in the Levant include: The Greek settlers would be used to form the Seleucid phalanx and cavalry units, with picked men put into the kingdom's guards' regiments. While the Seleucids were happy to recruit from smaller groups and outlying parts of the Empire such as Arabs and Jews, as well as Iranians from Central Asia and the people of Asia Minor; they generally eschewed recruiting Syrians (Arameans) and Babylonians. This was presumably from a desire not to train and arm the people who were an overwhelming majority in the trade and governmental centers of the Empire, in Antioch and Babylon, which would have undermined the empire's very existence in case of revolt. However, recruitment policy would become less strict by time of the Roman–Seleucid war (192–188 BC) The Seleucids gradually lost their domains in Bactria to the Greco-Bactrian Kingdom, and in Iran and Mesopotamia to the rising Parthian Empire. Eventually, this limited Seleucid domains to the Levant, and the power decline would lead to the formation of several breakaway states in the Levant. In the north, Greco-Iranian satrap Ptolemaeus declared himself the king of Commagene in 163 BC, while the Arab Abgarids ruled Osroene independently since 132 BC. The Maccabean Revolt in Judea inaugurated the Hasmonean kingdom in 140 BC. The Nabataeans further south had maintained their kingdom since the 3rd century BC. This rendered the Seleucids a weak, vulnerable state limited to parts of Syria and Lebanon. Roman period The Romans gained a foothold in the region in 64 BC after permanently defeating the Seleucids and Tigranes. Pompey deposed the last Seleucid king Philip II Philoromaeus, and incorporated Syria into Roman domains. However, the Romans only gradually incorporated local kingdoms into provinces, which gave them considerable autonomy in local affairs. The Herodian Kingdom of Judea replaced the Hasmonians in 37 BC until the full incorporation of Judea as Provincia Iudaea in 44 AD after Herod Agrippa II. Commagene and Osroene were incorporated as Roman provinces in 72 and 214 AD respectively, while Nabatea was incorporated as Arabia Petraea in 106 AD. Between the 1st and 3rd centuries the Levant prospered and flourished, reaching an estimated population of 3.5 to 6 million, which were only later matched by those of the 19th century. Urban centers peaked, and so did population density in the rural settlements. Antioch and Palmyra each reached a peak of 200,000–250,000 inhabitants, while Apamea counted 117,000 'free citizens' in AD 6. Combined with the dependencies and villages as well as slaves, Apamea may have, in fact, counted as high as 500,000. The Syrian Coastal Mountain Range, a marginal hill country, was less densely settled and had a population of around 40–50,000. According to Robert Kennedy, Palestine and the Transjordan accounted for roughly 800,000–1,200,000 of the population. The first to second centuries saw the emergence of a plethora of religions and philosophical schools. Neoplatonism emerged with Iamblichus and Porphyry, Neopythagorianism with Numenius of Apamea, and Hellenic Judaism with Philo of Alexandria. Christianity initially emerged as a sect of Judaism and finally as an independent religion by the mid-second century. Gnosticism also took significant hold in the region. The region of Palestine or Judea experienced abrupt periods of conflict between Romans and Jews. The First Jewish–Roman War (66–73) erupted in 66, resulting in the destruction of Jerusalem and the Second Temple in 70. Province forces were directly engaged in the war; in 66 AD, Cestius Gallus sent the Syrian army, based on Legio X Fretensis and Legio XII Fulminata reinforced by vexillationes of IV Scythica and VI Ferrata, to restore order in Judaea and quell the revolt, but suffered a defeat in the Battle of Beth Horon. However, XII Fulminata fought well in the last part of the war, and supported its commander Vespasian in his successful bid for the imperial throne. Two generations later, the Bar Kokhba revolt (132–136) erupted once again, after which the province Syria Palaestina was created in 132. During the Crisis of the Third Century, the Sassanids under Shapur I invaded the Levant and captured Roman emperor Valerian in the Battle of Edessa. A Syrian notable of Palmyra, Odaenathus assembled the Palmyrene army and Syrian peasants, and marched north to meet Shapur I. The Palmyrene monarch fell upon the retreating Persian army between Samosata and Zeugma, west of the Euphrates, in late summer 260, defeating and expelling them. After eliminating Roman usurpers in Syria –Balista and Quietus– in 261, Odaeanathus penetrated the Sassanid province of Asōristān in late 262 and laid siege to the Sassanid capital, Ctesiphon in 263. However, logistical problems meant the siege could not continue for long, and soon after Odaenathus broke the siege and brought numerous prisoners and booty to Rome. After his return, Odaenathus assumed the title of King of Kings of the East (Mlk Mlk dy Mdnh / Rex Regum). Odaenathus was succeeded by his son Vaballathus under the regency of his mother Queen Zenobia. In 270, Zenobia detached from Roman authority and declared the Palmyrene Empire, rapidly conquering much of Syria, Egypt, Arabia Petraea and large parts of Asia Minor, reaching present-day Ankara. However, by 273, Zenobia was decisively defeated by Aurelian and his Arab Tanukhid allies in Syria. Byzantine period Following the permanent division of the Roman Empire in 391, the Levantine provinces became part of the Byzantine Empire. In the southern Levant, a newly established foederati were crystallizing, the Ghassanid Arabs. The Ghassanids became a client state of the Byzantines, and served as a bulwark against Sassanid incursions and raids by nomads. With the consolidation of Christianity, Jews had become a minority in southern Levant, remaining a majority only in Southern Judea, Galilee and Golan. Jewish revolts had also become much rarer, mostly with the Jewish revolt against Constantius Gallus (351–352) and Jewish revolt against Heraclius (617). This time the Samaritans, whose population swelled to over a million, insurrected the Samaritan revolts (484–572) against the Byzantines, which killed an estimated 200,000 Samaritans, after the civil uprising of Baba Rabba and his subsequent execution in 328/362. The devastating Byzantine–Sasanian War of 602–628 ended with Byzantine recapture of the land, but left the empire rather exhausted, which taxed the inhabitants heavily. The Levant became the frontline between the Byzantines and the Persian Sassanids, which devastated the region. The war triggered the displacement of many inhabitants from Syria and Palestine to Egypt, and from there to Carthage and Sicily, although archaeological evidence suggests smooth continuity and little displacement of the overall population. Muslim conquest and period Eastern Roman control over the Levant lasted until 638 when Arab armies conquered the Levant, after which it became a part of the Rashidun Caliphate and was known as Bilād ash-Shām. Under the Umayyads, the capital was moved to Damascus. However, the Levant did not experience wide-scale Arabian tribal settlement unlike in Iraq, where the focus of Arabian tribal migration was. Archaeological and historical evidence strongly suggest there was smooth population continuity and no large-scale abandonment of major sites and regions of the Levant after the Muslim conquest. Moreover, in contrast to Iran, Iraq and North Africa, where Muslim soldiers established separate garrison cities (amsar), Muslim troops in the Levant settled alongside locals in pre-existing cities such as Damascus, Homs, Jerusalem and Tiberias. The Umayyads also relied on the native Syrian Arab tribes for their military, who oversaw a recruitment policy that resulted in considerable numbers of tribesmen and frontier peasants filling the ranks of the regular and auxiliary forces. These were Arab tribes who inhabited the Levant before Islam, and included tribes such as Lakhm, Judham, Ghassan, Amilah, Balqayn, Salih and Tanukh. When the Abbasids moved the capital to Baghdad in 750, this exposed the Muslim Arabs to the challenge of the strong and well-articulated identity of Iran, whereas in Damascus, they had only to contend with the numerous parochial and fractured identities of the Levant. Abbasid focus on Iraq and Iran neglected the Levant, which in turn experienced a period of frequent uprisings and revolts. Syria became fertile grounds for anti-Abbasid sentiments, in various contrasting pro-Umayyad and pro-Shiite forms. In 841, al-Mubarqa ('the Veiled One') lead a rebellion against the Abbasids in Palestine, declaring himself the Umayyad Sufyani. In 912, a revolt against the Abbasids arose in the Damascus region, this time by an Alid descendant of tenth Shiite Imam Ali al-Hadi. The growing Isma'ili dawah moved to the town of Salamiyah as its headquarters in 765, binding missionaries over to Iraq, Khuzestan, Yemen, Egypt and Maghreb. From Salamiyah, Isma'ili Imam Abd Allah al-Mahdi Billah moved to Sijilmasa in Morocco in 904, where his missionaries were active in proselytizing Berber tribes, eventually establishing the Fatimid empire by 909. See also References External links |
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Contents Minecraft Minecraft is a sandbox game developed and published by Mojang Studios. Following its initial public alpha release in 2009, it was formally released in 2011 for personal computers. The game has since been ported to numerous platforms, including mobile devices and various video game consoles. In Minecraft, players explore a procedurally generated world with virtually infinite terrain made up of voxels (cubes). They can discover and extract raw materials, craft tools and items, build structures, fight hostile mobs, and cooperate with or compete against other players in multiplayer. The game's large community offers a wide variety of user-generated content, such as modifications, servers, player skins, texture packs, and custom maps, which add new game mechanics and possibilities. Originally created by Markus "Notch" Persson using the Java programming language, Jens "Jeb" Bergensten was handed control over the game's development following its full release. In 2014, Mojang and the Minecraft intellectual property were purchased by Microsoft for US$2.5 billion; Xbox Game Studios hold the publishing rights for the Bedrock Edition, the unified cross-platform version which evolved from the Pocket Edition codebase[i] and replaced the legacy console versions. Bedrock is updated concurrently with Mojang's original Java Edition, although with numerous, generally small, differences. Minecraft is the best-selling video game in history with over 350 million copies sold. It has received critical acclaim, winning several awards and being cited as one of the greatest video games of all time. Social media, parodies, adaptations, merchandise, and the annual Minecon conventions have played prominent roles in popularizing it. The wider Minecraft franchise includes several spin-off games, such as Minecraft: Story Mode, Minecraft Dungeons, and Minecraft Legends. A film adaptation, titled A Minecraft Movie, was released in 2025 and became the second highest-grossing video game film of all time. Gameplay Minecraft is a 3D sandbox video game that has no required goals to accomplish, giving players a large amount of freedom in choosing how to play the game. The game features an optional achievement system. Gameplay is in the first-person perspective by default, but players have the option of third-person perspectives. The game world is composed of rough 3D objects—mainly cubes, referred to as blocks—representing various materials, such as dirt, stone, ores, tree trunks, water, and lava. The core gameplay revolves around picking up and placing these objects. These blocks are arranged in a voxel grid, while players can move freely around the world. Players can break, or mine, blocks and then place them elsewhere, enabling them to build things. Very few blocks are affected by gravity, instead maintaining their voxel position in the air. Players can also craft a wide variety of items, such as armor, which mitigates damage from attacks; weapons (such as swords or bows and arrows), which allow monsters and animals to be killed more easily; and tools (such as pickaxes or shovels), which break certain types of blocks more quickly. Some items have multiple tiers depending on the material used to craft them, with higher-tier items being more effective and durable. They may also freely craft helpful blocks—such as furnaces which can cook food and smelt ores, and torches that produce light—or exchange items with villagers (NPC) through trading emeralds for different goods and vice versa. The game has an inventory system, allowing players to carry a limited number of items. The in-game time system follows a day and night cycle, with one full cycle lasting for 20 real-time minutes. The game also contains a material called redstone, which can be used to make primitive mechanical devices, electrical circuits, and logic gates, allowing for the construction of many complex systems. New players are given a randomly selected default character skin out of nine possibilities, including Steve or Alex, but are able to create and upload their own skins. Players encounter various mobs (short for mobile entities) including animals, villagers, and hostile creatures. Passive mobs, such as cows, pigs, and chickens, spawn during the daytime and can be hunted for food and crafting materials, while hostile mobs—including large spiders, witches, skeletons, and zombies—spawn during nighttime or in dark places such as caves. Some hostile mobs, such as zombies and skeletons, burn under the sun if they have no headgear and are not standing in water. Other creatures unique to Minecraft include the creeper (an exploding creature that sneaks up on the player) and the enderman (a creature with the ability to teleport as well as pick up and place blocks). There are also variants of mobs that spawn in different conditions; for example, zombies have husk and drowned variants that spawn in deserts and oceans, respectively. The Minecraft environment is procedurally generated as players explore it using a map seed that is randomly chosen at the time of world creation (or manually specified by the player). Divided into biomes representing different environments with unique resources and structures, worlds are designed to be effectively infinite in traditional gameplay, though technical limits on the player have existed throughout development, both intentionally and not. Implementation of horizontally infinite generation initially resulted in a glitch termed the "Far Lands" at over 12 million blocks away from the world center, where terrain generated as wall-like, fissured patterns. The Far Lands and associated glitches were considered the effective edge of the world until they were resolved, with the current horizontal limit instead being a special impassable barrier called the world border, located 30 million blocks away. Vertical space is comparatively limited, with an unbreakable bedrock layer at the bottom and a building limit several hundred blocks into the sky. Minecraft features three independent dimensions accessible through portals and providing alternate game environments. The Overworld is the starting dimension and represents the real world, with a terrestrial surface setting including plains, mountains, forests, oceans, caves, and small sources of lava. The Nether is a hell-like underworld dimension accessed via an obsidian portal and composed mainly of lava. Mobs that populate the Nether include shrieking, fireball-shooting ghasts, alongside anthropomorphic pigs called piglins and their zombified counterparts. Piglins in particular have a bartering system, where players can give them gold ingots and receive items in return. Structures known as Nether Fortresses generate in the Nether, containing mobs such as wither skeletons and blazes, which can drop blaze rods needed to access the End dimension. The player can also choose to build an optional boss mob known as the Wither, using skulls obtained from wither skeletons and soul sand. The End can be reached through an end portal, consisting of twelve end portal frames. End portals are found in underground structures in the Overworld known as strongholds. To find strongholds, players must craft eyes of ender using an ender pearl and blaze powder. Eyes of ender can then be thrown, traveling in the direction of the stronghold. Once the player reaches the stronghold, they can place eyes of ender into each portal frame to activate the end portal. The dimension consists of islands floating in a dark, bottomless void. A boss enemy called the Ender Dragon guards the largest, central island. Killing the dragon opens access to an exit portal, which, when entered, cues the game's ending credits and the End Poem, a roughly 1,500-word work written by Irish novelist Julian Gough, which takes about nine minutes to scroll past, is the game's only narrative text, and the only text of significant length directed at the player.: 10–12 At the conclusion of the credits, the player is teleported back to their respawn point and may continue the game indefinitely. In Survival mode, players have to gather natural resources such as wood and stone found in the environment in order to craft certain blocks and items. Depending on the difficulty, monsters spawn in darker areas outside a certain radius of the character, requiring players to build a shelter in order to survive at night. The mode also has a health bar which is depleted by attacks from mobs, falls, drowning, falling into lava, suffocation, starvation, and other events. Players also have a hunger bar, which must be periodically refilled by eating food in-game unless the player is playing on peaceful difficulty. If the hunger bar is empty, the player starves. Health replenishes when players have a full hunger bar or continuously on peaceful. Upon losing all health, players die. The items in the players' inventories are dropped unless the game is reconfigured not to do so. Players then re-spawn at their spawn point, which by default is where players first spawn in the game and can be changed by sleeping in a bed or using a respawn anchor. Dropped items can be recovered if players can reach them before they despawn after 5 minutes. Players may acquire experience points (commonly referred to as "xp" or "exp") by killing mobs and other players, mining, smelting ores, animal breeding, and cooking food. Experience can then be spent on enchanting tools, armor and weapons. Enchanted items are generally more powerful, last longer, or have other special effects. The game features two more game modes based on Survival, known as Hardcore mode and Adventure mode. Hardcore mode plays identically to Survival mode, but with the game's difficulty setting locked to "Hard" and with permadeath, forcing them to delete the world or explore it as a spectator after dying. Adventure mode was added to the game in a post-launch update, and prevents the player from directly modifying the game's world. It was designed primarily for use in custom maps, allowing map designers to let players experience it as intended. In Creative mode, players have access to an infinite number of all resources and items in the game through the inventory menu and can place or mine them instantly. Players can toggle the ability to fly freely around the game world at will, and their characters usually do not take any damage nor are affected by hunger. The game mode helps players focus on building and creating projects of any size without disturbance. Multiplayer in Minecraft enables multiple players to interact and communicate with each other on a single world. It is available through direct game-to-game multiplayer, local area network (LAN) play, local split screen (console-only), and servers (player-hosted and business-hosted). Players can run their own server by making a realm, using a host provider, hosting one themselves or connect directly to another player's game via Xbox Live, PlayStation Network or Nintendo Switch Online. Single-player worlds have LAN support, allowing players to join a world on locally interconnected computers without a server setup. Minecraft multiplayer servers are guided by server operators, who have access to server commands such as setting the time of day and teleporting players. Operators can also set up restrictions concerning which usernames or IP addresses are allowed or disallowed to enter the server. Multiplayer servers have a wide range of activities, with some servers having their own unique rules and customs. The largest and most popular server is Hypixel, which has been visited by over 14 million unique players. Player versus player combat (PvP) can be enabled to allow fighting between players. In 2013, Mojang announced Minecraft Realms, a server hosting service intended to enable players to run server multiplayer games easily and safely without having to set up their own. Unlike a standard server, only invited players can join Realms servers, and these servers do not use server addresses. Minecraft: Java Edition Realms server owners can invite up to twenty people to play on their server, with up to ten players online at a time. Minecraft Realms server owners can invite up to 3,000 people to play on their server, with up to ten players online at one time. The Minecraft: Java Edition Realms servers do not support user-made plugins, but players can play custom Minecraft maps. Minecraft Bedrock Realms servers support user-made add-ons, resource packs, behavior packs, and custom Minecraft maps. At Electronic Entertainment Expo 2016, support for cross-platform play between Windows 10, iOS, and Android platforms was added through Realms starting in June 2016, with Xbox One and Nintendo Switch support to come later in 2017, and support for virtual reality devices. On 31 July 2017, Mojang released the beta version of the update allowing cross-platform play. Nintendo Switch support for Realms was released in July 2018. The modding community consists of fans, users and third-party programmers. Using a variety of application program interfaces that have arisen over time, they have produced a wide variety of downloadable content for Minecraft, such as modifications, texture packs and custom maps. Modifications of the Minecraft code, called mods, add a variety of gameplay changes, ranging from new blocks, items, and mobs to entire arrays of mechanisms. The modding community is responsible for a substantial supply of mods from ones that enhance gameplay, such as mini-maps, waypoints, and durability counters, to ones that add to the game elements from other video games and media. While a variety of mod frameworks were independently developed by reverse engineering the code, Mojang has also enhanced vanilla Minecraft with official frameworks for modification, allowing the production of community-created resource packs, which alter certain game elements including textures and sounds. Players can also create their own "maps" (custom world save files) that often contain specific rules, challenges, puzzles and quests, and share them for others to play. Mojang added an adventure mode in August 2012 and "command blocks" in October 2012, which were created specially for custom maps in Java Edition. Data packs, introduced in version 1.13 of the Java Edition, allow further customization, including the ability to add new achievements, dimensions, functions, loot tables, predicates, recipes, structures, tags, and world generation. The Xbox 360 Edition supported downloadable content, which was available to purchase via the Xbox Games Store; these content packs usually contained additional character skins. It later received support for texture packs in its twelfth title update while introducing "mash-up packs", which combined texture packs with skin packs and changes to the game's sounds, music and user interface. The first mash-up pack (and by extension, the first texture pack) for the Xbox 360 Edition was released on 4 September 2013, and was themed after the Mass Effect franchise. Unlike Java Edition, however, the Xbox 360 Edition did not support player-made mods or custom maps. A cross-promotional resource pack based on the Super Mario franchise by Nintendo was released exclusively for the Wii U Edition worldwide on 17 May 2016, and later bundled free with the Nintendo Switch Edition at launch. Another based on Fallout was released on consoles that December, and for Windows and Mobile in April 2017. In April 2018, malware was discovered in several downloadable user-made Minecraft skins for use with the Java Edition of the game. Avast stated that nearly 50,000 accounts were infected, and when activated, the malware would attempt to reformat the user's hard drive. Mojang promptly patched the issue, and released a statement stating that "the code would not be run or read by the game itself", and would run only when the image containing the skin itself was opened. In June 2017, Mojang released the "1.1 Discovery Update" to the Pocket Edition of the game, which later became the Bedrock Edition. The update introduced the "Marketplace", a catalogue of purchasable user-generated content intended to give Minecraft creators "another way to make a living from the game". Various skins, maps, texture packs and add-ons from different creators can be bought with "Minecoins", a digital currency that is purchased with real money. Additionally, users can access specific content with a subscription service titled "Marketplace Pass". Alongside content from independent creators, the Marketplace also houses items published by Mojang and Microsoft themselves, as well as official collaborations between Minecraft and other intellectual properties. By 2022, the Marketplace had over 1.7 billion content downloads, generating over $500 million in revenue. Development Before creating Minecraft, Markus "Notch" Persson was a game developer at King, where he worked until March 2009. At King, he primarily developed browser games and learned several programming languages. During his free time, he prototyped his own games, often drawing inspiration from other titles, and was an active participant on the TIGSource forums for independent developers. One such project was "RubyDung", a base-building game inspired by Dwarf Fortress, but with an isometric, three-dimensional perspective similar to RollerCoaster Tycoon. Among the features in RubyDung that he explored was a first-person view similar to Dungeon Keeper, though he ultimately discarded this idea, feeling the graphics were too pixelated at the time. Around March 2009, Persson left King and joined jAlbum, while continuing to work on his prototypes. Infiniminer, a block-based open-ended mining game first released in April 2009, inspired Persson's vision for RubyDung's future direction. Infiniminer heavily influenced the visual style of gameplay, including bringing back the first-person mode, the "blocky" visual style and the block-building fundamentals. However, unlike Infiniminer, Persson wanted Minecraft to have RPG elements. The first public alpha build of Minecraft was released on 17 May 2009 on TIGSource. Over the years, Persson regularly released test builds that added new features, including tools, mobs, and entire new dimensions. In 2011, partly due to the game's rising popularity, Persson decided to release a full 1.0 version—a second part of the "Adventure Update"—on 18 November 2011. Shortly after, Persson stepped down from development, handing the project's lead to Jens "Jeb" Bergensten. On 15 September 2014, Microsoft, the developer behind the Microsoft Windows operating system and Xbox video game console, announced a $2.5 billion acquisition of Mojang, which included the Minecraft intellectual property. Persson had suggested the deal on Twitter, asking a corporation to buy his stake in the game after receiving criticism for enforcing terms in the game's end-user license agreement (EULA), which had been in place for the past three years. According to Persson, Mojang CEO Carl Manneh received a call from a Microsoft executive shortly after the tweet, asking if Persson was serious about a deal. Mojang was also approached by other companies including Activision Blizzard and Electronic Arts. The deal with Microsoft was arbitrated on 6 November 2014 and led to Persson becoming one of Forbes' "World's Billionaires". After 2014, Minecraft's primary versions received usually annual major updates—free to players who have purchased the game— each primarily centered around a specific theme. For instance, version 1.13, the Update Aquatic, focused on ocean-related features, while version 1.16, the Nether Update, introduced significant changes to the Nether dimension. However, in late 2024, Mojang announced a shift in their update strategy; rather than releasing large updates annually, they opted for a more frequent release schedule with smaller, incremental updates, stating, "We know that you want new Minecraft content more often." The Bedrock Edition has also received regular updates, now matching the themes of the Java Edition updates. Other versions of the game, such as various console editions and the Pocket Edition, were either merged into Bedrock or discontinued and have not received further updates. On 7 May 2019, coinciding with Minecraft's 10th anniversary, a JavaScript recreation of an old 2009 Java Edition build named Minecraft Classic was made available to play online for free. On 16 April 2020, a Bedrock Edition-exclusive beta version of Minecraft, called Minecraft RTX, was released by Nvidia. It introduced physically-based rendering, real-time path tracing, and DLSS for RTX-enabled GPUs. The public release was made available on 8 December 2020. Path tracing can only be enabled in supported worlds, which can be downloaded for free via the in-game Minecraft Marketplace, with a texture pack from Nvidia's website, or with compatible third-party texture packs. It cannot be enabled by default with any texture pack on any world. Initially, Minecraft RTX was affected by many bugs, display errors, and instability issues. On 22 March 2025, a new visual mode called Vibrant Visuals, an optional graphical overhaul similar to Minecraft RTX, was announced. It promises modern rendering features—such as dynamic shadows, screen space reflections, volumetric fog, and bloom—without the need of RTX-capable hardware. Vibrant Visuals was released as a part of the Chase the Skies update on 17 June 2025 for Bedrock Edition and is planned to release on Java Edition at a later date. Development began for the original edition of Minecraft—then known as Cave Game, and now known as the Java Edition—in May 2009,[k] and ended on 13 May, when Persson released a test video on YouTube of an early version of the game, dubbed the "Cave game tech test" or the "Cave game tech demo". The game was named Minecraft: Order of the Stone the next day, after a suggestion made by a player. "Order of the Stone" came from the webcomic The Order of the Stick, and "Minecraft" was chosen "because it's a good name". The title was later shortened to just Minecraft, omitting the subtitle. Persson completed the game's base programming over a weekend in May 2009, and private testing began on TigIRC on 16 May. The first public release followed on 17 May 2009 as a developmental version shared on the TIGSource forums. Based on feedback from forum users, Persson continued updating the game. This initial public build later became known as Classic. Further developmental phases—dubbed Survival Test, Indev, and Infdev—were released throughout 2009 and 2010. The first major update, known as Alpha, was released on 30 June 2010. At the time, Persson was still working a day job at jAlbum but later resigned to focus on Minecraft full-time as sales of the alpha version surged. Updates were distributed automatically, introducing new blocks, items, mobs, and changes to game mechanics such as water flow. With revenue generated from the game, Persson founded Mojang, a video game studio, alongside former colleagues Jakob Porser and Carl Manneh. On 11 December 2010, Persson announced that Minecraft would enter its beta phase on 20 December. He assured players that bug fixes and all pre-release updates would remain free. As development progressed, Mojang expanded, hiring additional employees to work on the project. The game officially exited beta and launched in full on 18 November 2011. On 1 December 2011, Jens "Jeb" Bergensten took full creative control over Minecraft, replacing Persson as lead designer. On 28 February 2012, Mojang announced the hiring of the developers behind Bukkit, a popular developer API for Minecraft servers, to improve Minecraft's support of server modifications. This move included Mojang taking apparent ownership of the CraftBukkit server mod, though this apparent acquisition later became controversial, and its legitimacy was questioned due to CraftBukkit's open-source nature and licensing under the GNU General Public License and Lesser General Public License. In August 2011, Minecraft: Pocket Edition was released as an early alpha for the Xperia Play via the Android Market, later expanding to other Android devices on 8 October 2011. The iOS version followed on 17 November 2011. A port was made available for Windows Phones shortly after Microsoft acquired Mojang. Unlike Java Edition, Pocket Edition initially focused on Minecraft's creative building and basic survival elements but lacked many features of the PC version. Bergensten confirmed on Twitter that the Pocket Edition was written in C++ rather than Java, as iOS does not support Java. On 10 December 2014, a port of Pocket Edition was released for Windows Phone 8.1. In July 2015, a port of the Pocket Edition to Windows 10 was released as the Windows 10 Edition, with full crossplay to other Pocket versions. In January 2017, Microsoft announced that it would no longer maintain the Windows Phone versions of Pocket Edition. On 20 September 2017, with the "Better Together Update", the Pocket Edition was ported to the Xbox One, and was renamed to the Bedrock Edition. The console versions of Minecraft debuted with the Xbox 360 edition, developed by 4J Studios and released on 9 May 2012. Announced as part of the Xbox Live Arcade NEXT promotion, this version introduced a redesigned crafting system, a new control interface, in-game tutorials, split-screen multiplayer, and online play via Xbox Live. Unlike the PC version, its worlds were finite, bordered by invisible walls. Initially, the Xbox 360 version resembled outdated PC versions but received updates to bring it closer to Java Edition before eventually being discontinued. The Xbox One version launched on 5 September 2014, featuring larger worlds and support for more players. Minecraft expanded to PlayStation platforms with PlayStation 3 and PlayStation 4 editions released on 17 December 2013 and 4 September 2014, respectively. Originally planned as a PS4 launch title, it was delayed before its eventual release. A PlayStation Vita version followed in October 2014. Like the Xbox versions, the PlayStation editions were developed by 4J Studios. Nintendo platforms received Minecraft: Wii U Edition on 17 December 2015, with a physical release in North America on 17 June 2016 and in Europe on 30 June. The Nintendo Switch version launched via the eShop on 11 May 2017. During a Nintendo Direct presentation on 13 September 2017, Nintendo announced that Minecraft: New Nintendo 3DS Edition, based on the Pocket Edition, would be available for download immediately after the livestream, and a physical copy available on a later date. The game is compatible only with the New Nintendo 3DS or New Nintendo 2DS XL systems and does not work with the original 3DS or 2DS systems. On 20 September 2017, the Better Together Update introduced Bedrock Edition across Xbox One, Windows 10, VR, and mobile platforms, enabling cross-play between these versions. Bedrock Edition later expanded to Nintendo Switch and PlayStation 4, with the latter receiving the update in December 2019, allowing cross-platform play for users with a free Xbox Live account. The Bedrock Edition released a native version for PlayStation 5 on 22 October 2024, while the Xbox Series X/S version launched on 17 June 2025. On 18 December 2018, the PlayStation 3, PlayStation Vita, Xbox 360, and Wii U versions of Minecraft received their final update and would later become known as "Legacy Console Editions". On 15 January 2019, the New Nintendo 3DS version of Minecraft received its final update, effectively becoming discontinued as well. An educational version of Minecraft, designed for use in schools, launched on 1 November 2016. It is available on Android, ChromeOS, iPadOS, iOS, MacOS, and Windows. On 20 August 2018, Mojang announced that it would bring Education Edition to iPadOS in Autumn 2018. It was released to the App Store on 6 September 2018. On 27 March 2019, it was announced that it would be operated by JD.com in China. On 26 June 2020, a public beta for the Education Edition was made available to Google Play Store compatible Chromebooks. The full game was released to the Google Play Store for Chromebooks on 7 August 2020. On 20 May 2016, China Edition (also known as My World) was announced as a localized edition for China, where it was released under a licensing agreement between NetEase and Mojang. The PC edition was released for public testing on 8 August 2017. The iOS version was released on 15 September 2017, and the Android version was released on 12 October 2017. The PC edition is based on the original Java Edition, while the iOS and Android mobile versions are based on the Bedrock Edition. The edition is free-to-play and had over 700 million registered accounts by September 2023. This version of Bedrock Edition is exclusive to Microsoft's Windows 10 and Windows 11 operating systems. The beta release for Windows 10 launched on the Windows Store on 29 July 2015. After nearly a year and a half in beta, Microsoft fully released the version on 19 December 2016. Called the "Ender Update", this release implemented new features to this version of Minecraft like world templates and add-on packs. On 7 June 2022, the Java and Bedrock Editions of Minecraft were merged into a single bundle for purchase on Windows; those who owned one version would automatically gain access to the other version. Both game versions would otherwise remain separate. Around 2011, prior to Minecraft's full release, Mojang collaborated with The Lego Group to create a Lego brick-based Minecraft game called Brickcraft. This would have modified the base Minecraft game to use Lego bricks, which meant adapting the basic 1×1 block to account for larger pieces typically used in Lego sets. Persson worked on an early version called "Project Rex Kwon Do", named after the character of the same name from the film Napoleon Dynamite. Although Lego approved the project and Mojang assigned two developers for six months, it was canceled due to the Lego Group's demands, according to Mojang's Daniel Kaplan. Lego considered buying Mojang to complete the game, but when Microsoft offered over $2 billion for the company, Lego stepped back, unsure of Minecraft's potential. On 26 June 2025, a build of Brickcraft dated 28 June 2012 was published on a community archive website Omniarchive. Initially, Markus Persson planned to support the Oculus Rift with a Minecraft port. However, after Facebook acquired Oculus in 2013, he abruptly canceled the plans, stating, "Facebook creeps me out." In 2016, a community-made mod, Minecraft VR, added VR support for Java Edition, followed by Vivecraft for HTC Vive. Later that year, Microsoft introduced official Oculus Rift support for Windows 10 Edition, leading to the discontinuation of the Minecraft VR mod due to trademark complaints. Vivecraft was endorsed by Minecraft VR contributors for its Rift support. Also available is a Gear VR version, titled Minecraft: Gear VR Edition. Windows Mixed Reality support was added in 2017. On 7 September 2020, Mojang Studios announced that the PlayStation 4 Bedrock version would receive PlayStation VR support later that month. In September 2024, the Minecraft team announced they would no longer support PlayStation VR, which received its final update in March 2025. Music and sound design Minecraft's music and sound effects were produced by German musician Daniel Rosenfeld, better known as C418. To create the sound effects for the game, Rosenfeld made extensive use of Foley techniques. On learning the processes for the game, he remarked, "Foley's an interesting thing, and I had to learn its subtleties. Early on, I wasn't that knowledgeable about it. It's a whole trial-and-error process. You just make a sound and eventually you go, 'Oh my God, that's it! Get the microphone!' There's no set way of doing anything at all." He reminisced on creating the in-game sound for grass blocks, stating "It turns out that to make grass sounds you don't actually walk on grass and record it, because grass sounds like nothing. What you want to do is get a VHS, break it apart, and just lightly touch the tape." According to Rosenfeld, his favorite sound to design for the game was the hisses of spiders. He elaborates, "I like the spiders. Recording that was a whole day of me researching what a spider sounds like. Turns out, there are spiders that make little screeching sounds, so I think I got this recording of a fire hose, put it in a sampler, and just pitched it around until it sounded like a weird spider was talking to you." Many of the sound design decisions by Rosenfeld were done accidentally or spontaneously. The creeper notably lacks any specific noises apart from a loud fuse-like sound when about to explode; Rosenfeld later recalled "That was just a complete accident by Markus and me [sic]. We just put in a placeholder sound of burning a matchstick. It seemed to work hilariously well, so we kept it." On other sounds, such as those of the zombie, Rosenfeld remarked, "I actually never wanted the zombies so scary. I intentionally made them sound comical. It's nice to hear that they work so well [...]." Rosenfeld remarked that the sound engine was "terrible" to work with, remembering "If you had two song files at once, it [the game engine] would actually crash. There were so many more weird glitches like that the guys never really fixed because they were too busy with the actual game and not the sound engine." The background music in Minecraft consists of instrumental ambient music. To compose the music of Minecraft, Rosenfeld used the package from Ableton Live, along with several additional plug-ins. Speaking on them, Rosenfeld said "They can be pretty much everything from an effect to an entire orchestra. Additionally, I've got some synthesizers that are attached to the computer. Like a Moog Voyager, Dave Smith Prophet 08 and a Virus TI." On 4 March 2011, Rosenfeld released a soundtrack titled Minecraft – Volume Alpha; it includes most of the tracks featured in Minecraft, as well as other music not featured in the game. Kirk Hamilton of Kotaku chose the music in Minecraft as one of the best video game soundtracks of 2011. On 9 November 2013, Rosenfeld released the second official soundtrack, titled Minecraft – Volume Beta, which included the music that was added in a 2013 "Music Update" for the game. A physical release of Volume Alpha, consisting of CDs, black vinyl, and limited-edition transparent green vinyl LPs, was issued by indie electronic label Ghostly International on 21 August 2015. On 14 August 2020, Ghostly released Volume Beta on CD and vinyl, with alternate color LPs and lenticular cover pressings released in limited quantities. The final update Rosenfeld worked on was 2018's 1.13 Update Aquatic. His music remained the only music in the game until 2020's "Nether Update", introducing pieces from Lena Raine. Since then, other composers have made contributions, including Kumi Tanioka, Samuel Åberg, Aaron Cherof, and Amos Roddy, with Raine remaining as the new primary composer. Ownership of all music besides Rosenfeld's independently released albums has been retained by Microsoft, with their label publishing all of the other artists' releases. Gareth Coker also composed some of the music for the game's mini games from the Legacy Console editions. Rosenfeld had stated his intent to create a third album of music for the game in a 2015 interview with Fact, and confirmed its existence in a 2017 tweet, stating that his work on the record as of then had tallied up to be longer than the previous two albums combined, which in total clocks in at over 3 hours and 18 minutes. However, due to licensing issues with Microsoft, the third volume has since not seen release. On 8 January 2021, Rosenfeld was asked in an interview with Anthony Fantano whether or not there was still a third volume of his music intended for release. Rosenfeld responded, saying, "I have something—I consider it finished—but things have become complicated, especially as Minecraft is now a big property, so I don't know." Reception Minecraft has received critical acclaim, with praise for the creative freedom it grants players in-game, as well as the ease of enabling emergent gameplay. Critics have expressed enjoyment in Minecraft's complex crafting system, commenting that it is an important aspect of the game's open-ended gameplay. Most publications were impressed by the game's "blocky" graphics, with IGN describing them as "instantly memorable". Reviewers also liked the game's adventure elements, noting that the game creates a good balance between exploring and building. The game's multiplayer feature has been generally received favorably, with IGN commenting that "adventuring is always better with friends". Jaz McDougall of PC Gamer said Minecraft is "intuitively interesting and contagiously fun, with an unparalleled scope for creativity and memorable experiences". It has been regarded as having introduced millions of children to the digital world, insofar as its basic game mechanics are logically analogous to computer commands. IGN was disappointed about the troublesome steps needed to set up multiplayer servers, calling it a "hassle". Critics also said that visual glitches occur periodically. Despite its release out of beta in 2011, GameSpot said the game had an "unfinished feel", adding that some game elements seem "incomplete or thrown together in haste". A review of the alpha version, by Scott Munro of the Daily Record, called it "already something special" and urged readers to buy it. Jim Rossignol of Rock Paper Shotgun also recommended the alpha of the game, calling it "a kind of generative 8-bit Lego Stalker". On 17 September 2010, gaming webcomic Penny Arcade began a series of comics and news posts about the addictiveness of the game. The Xbox 360 version was generally received positively by critics, but did not receive as much praise as the PC version. Although reviewers were disappointed by the lack of features such as mod support and content from the PC version, they acclaimed the port's addition of a tutorial and in-game tips and crafting recipes, saying that they make the game more user-friendly. The Xbox One Edition was one of the best received ports, being praised for its relatively large worlds. The PlayStation 3 Edition also received generally favorable reviews, being compared to the Xbox 360 Edition and praised for its well-adapted controls. The PlayStation 4 edition was the best received port to date, being praised for having 36 times larger worlds than the PlayStation 3 edition and described as nearly identical to the Xbox One edition. The PlayStation Vita Edition received generally positive reviews from critics but was noted for its technical limitations. The Wii U version received generally positive reviews from critics but was noted for a lack of GamePad integration. The 3DS version received mixed reviews, being criticized for its high price, technical issues, and lack of cross-platform play. The Nintendo Switch Edition received fairly positive reviews from critics, being praised, like other modern ports, for its relatively larger worlds. Minecraft: Pocket Edition initially received mixed reviews from critics. Although reviewers appreciated the game's intuitive controls, they were disappointed by the lack of content. The inability to collect resources and craft items, as well as the limited types of blocks and lack of hostile mobs, were especially criticized. After updates added more content, Pocket Edition started receiving more positive reviews. Reviewers complimented the controls and the graphics, but still noted a lack of content. Minecraft surpassed over a million purchases less than a month after entering its beta phase in early 2011. At the same time, the game had no publisher backing and has never been commercially advertised except through word of mouth, and various unpaid references in popular media such as the Penny Arcade webcomic. By April 2011, Persson estimated that Minecraft had made €23 million (US$33 million) in revenue, with 800,000 sales of the alpha version of the game, and over 1 million sales of the beta version. In November 2011, prior to the game's full release, Minecraft beta surpassed 16 million registered users and 4 million purchases. By March 2012, Minecraft had become the 6th best-selling PC game of all time. As of 10 October 2014[update], the game had sold 17 million copies on PC, becoming the best-selling PC game of all time. On 25 February 2014, the game reached 100 million registered users. By May 2019, 180 million copies had been sold across all platforms, making it the single best-selling video game of all time. The free-to-play Minecraft China version had over 700 million registered accounts by September 2023. By 2023, the game had sold over 300 million copies. As of April 2025, Minecraft has sold over 350 million copies. The Xbox 360 version of Minecraft became profitable within the first day of the game's release in 2012, when the game broke the Xbox Live sales records with 400,000 players online. Within a week of being on the Xbox Live Marketplace, Minecraft sold a million copies. GameSpot announced in December 2012 that Minecraft sold over 4.48 million copies since the game debuted on Xbox Live Arcade in May 2012. In 2012, Minecraft was the most purchased title on Xbox Live Arcade; it was also the fourth most played title on Xbox Live based on average unique users per day. As of 4 April 2014[update], the Xbox 360 version has sold 12 million copies. In addition, Minecraft: Pocket Edition has reached a figure of 21 million in sales. The PlayStation 3 Edition sold one million copies in five weeks. The release of the game's PlayStation Vita version boosted Minecraft sales by 79%, outselling both PS3 and PS4 debut releases and becoming the largest Minecraft launch on a PlayStation console. The PS Vita version sold 100,000 digital copies in Japan within the first two months of release, according to an announcement by SCE Japan Asia. By January 2015, 500,000 digital copies of Minecraft were sold in Japan across all PlayStation platforms, with a surge in primary school children purchasing the PS Vita version. As of 2022, the Vita version has sold over 1.65 million physical copies in Japan, making it the best-selling Vita game in the country. Minecraft helped improve Microsoft's total first-party revenue by $63 million for the 2015 second quarter. The game, including all of its versions, had over 112 million monthly active players by September 2019. On its 11th anniversary in May 2020, the company announced that Minecraft had reached over 200 million copies sold across platforms with over 126 million monthly active players. By April 2021, the number of active monthly users had climbed to 140 million. In July 2010, PC Gamer listed Minecraft as the fourth-best game to play at work. In December of that year, Good Game selected Minecraft as their choice for Best Downloadable Game of 2010, Gamasutra named it the eighth best game of the year as well as the eighth best indie game of the year, and Rock, Paper, Shotgun named it the "game of the year". Indie DB awarded the game the 2010 Indie of the Year award as chosen by voters, in addition to two out of five Editor's Choice awards for Most Innovative and Best Singleplayer Indie. It was also awarded Game of the Year by PC Gamer UK. The game was nominated for the Seumas McNally Grand Prize, Technical Excellence, and Excellence in Design awards at the March 2011 Independent Games Festival and won the Grand Prize and the community-voted Audience Award. At Game Developers Choice Awards 2011, Minecraft won awards in the categories for Best Debut Game, Best Downloadable Game and Innovation Award, winning every award for which it was nominated. It also won GameCity's video game arts award. On 5 May 2011, Minecraft was selected as one of the 80 games that would be displayed at the Smithsonian American Art Museum as part of The Art of Video Games exhibit that opened on 16 March 2012. At the 2011 Spike Video Game Awards, Minecraft won the award for Best Independent Game and was nominated in the Best PC Game category. In 2012, at the British Academy Video Games Awards, Minecraft was nominated in the GAME Award of 2011 category and Persson received The Special Award. In 2012, Minecraft XBLA was awarded a Golden Joystick Award in the Best Downloadable Game category, and a TIGA Games Industry Award in the Best Arcade Game category. In 2013, it was nominated as the family game of the year at the British Academy Video Games Awards. During the 16th Annual D.I.C.E. Awards, the Academy of Interactive Arts & Sciences nominated the Xbox 360 version of Minecraft for "Strategy/Simulation Game of the Year". Minecraft Console Edition won the award for TIGA Game Of The Year in 2014. In 2015, the game placed 6th on USgamer's The 15 Best Games Since 2000 list. In 2016, Minecraft placed 6th on Time's The 50 Best Video Games of All Time list. Minecraft was nominated for the 2013 Kids' Choice Awards for Favorite App, but lost to Temple Run. It was nominated for the 2014 Kids' Choice Awards for Favorite Video Game, but lost to Just Dance 2014. The game later won the award for the Most Addicting Game at the 2015 Kids' Choice Awards. In addition, the Java Edition was nominated for "Favorite Video Game" at the 2018 Kids' Choice Awards, while the game itself won the "Still Playing" award at the 2019 Golden Joystick Awards, as well as the "Favorite Video Game" award at the 2020 Kids' Choice Awards. Minecraft also won "Stream Game of the Year" at inaugural Streamer Awards in 2021. The game later garnered a Nickelodeon Kids' Choice Award nomination for Favorite Video Game in 2021, and won the same category in 2022 and 2023. At the Golden Joystick Awards 2025, it won the Still Playing Award - PC and Console. Minecraft has been subject to several notable controversies. In June 2014, Mojang announced that it would begin enforcing the portion of Minecraft's end-user license agreement (EULA) which prohibits servers from giving in-game advantages to players in exchange for donations or payments. Spokesperson Owen Hill stated that servers could still require players to pay a fee to access the server and could sell in-game cosmetic items. The change was supported by Persson, citing emails he received from parents of children who had spent hundreds of dollars on servers. The Minecraft community and server owners protested, arguing that the EULA's terms were more broad than Mojang was claiming, that the crackdown would force smaller servers to shut down for financial reasons, and that Mojang was suppressing competition for its own Minecraft Realms subscription service. The controversy contributed to Notch's decision to sell Mojang. In 2020, Mojang announced an eventual change to the Java Edition to require a login from a Microsoft account rather than a Mojang account, the latter of which would be sunsetted. This also required Java Edition players to create Xbox network Gamertags. Mojang defended the move to Microsoft accounts by saying that improved security could be offered, including two-factor authentication, blocking cyberbullies in chat, and improved parental controls. The community responded with intense backlash, citing various technical difficulties encountered in the process and how account migration would be mandatory, even for those who do not play on servers. As of 10 March 2022, Microsoft required that all players migrate in order to maintain access the Java Edition of Minecraft. Mojang announced a deadline of 19 September 2023 for account migration, after which all legacy Mojang accounts became inaccessible and unable to be migrated. In June 2022, Mojang added a player-reporting feature in Java Edition. Players could report other players on multiplayer servers for sending messages prohibited by the Xbox Live Code of Conduct; report categories included profane language,[l] substance abuse, hate speech, threats of violence, and nudity. If a player was found to be in violation of Xbox Community Standards, they would be banned from all servers for a specific period of time or permanently. The update containing the report feature (1.19.1) was released on 27 July 2022. Mojang received substantial backlash and protest from community members, one of the most common complaints being that banned players would be forbidden from joining any server, even private ones. Others took issue to what they saw as Microsoft increasing control over its player base and exercising censorship, leading some to start a hashtag #saveminecraft and dub the version "1.19.84", a reference to the dystopian novel Nineteen Eighty-Four. The "Mob Vote" was an online event organized by Mojang in which the Minecraft community voted between three original mob concepts; initially, the winning mob was to be implemented in a future update, while the losing mobs were scrapped, though after the first mob vote this was changed, and losing mobs would now have a chance to come to the game in the future. The first Mob Vote was held during Minecon Earth 2017 and became an annual event starting with Minecraft Live 2020. The Mob Vote was often criticized for forcing players to choose one mob instead of implementing all three, causing divisions and flaming within the community, and potentially allowing internet bots and Minecraft content creators with large fanbases to conduct vote brigading. The Mob Vote was also blamed for a perceived lack of new content added to Minecraft since Microsoft's acquisition of Mojang in 2014. The 2023 Mob Vote featured three passive mobs—the crab, the penguin, and the armadillo—with voting scheduled to start on 13 October. In response, a Change.org petition was created on 6 October, demanding that Mojang eliminate the Mob Vote and instead implement all three mobs going forward. The petition received approximately 445,000 signatures by 13 October and was joined by calls to boycott the Mob Vote, as well as a partially tongue-in-cheek "revolutionary" propaganda campaign in which sympathizers created anti-Mojang and pro-boycott posters in the vein of real 20th century propaganda posters. Mojang did not release an official response to the boycott, and the Mob Vote otherwise proceeded normally, with the armadillo winning the vote. In September 2024, as part of a blog post detailing their future plans for Minecraft's development, Mojang announced the Mob Vote would be retired. Cultural impact In September 2019, The Guardian classified Minecraft as the best video game of the 21st century to date, and in November 2019, Polygon called it the "most important game of the decade" in its 2010s "decade in review". In June 2020, Minecraft was inducted into the World Video Game Hall of Fame. Minecraft is recognized as one of the first successful games to use an early access model to draw in sales prior to its full release version to help fund development. As Minecraft helped to bolster indie game development in the early 2010s, it also helped to popularize the use of the early access model in indie game development. Social media sites such as YouTube, Facebook, and Reddit have played a significant role in popularizing Minecraft. Research conducted by the Annenberg School for Communication at the University of Pennsylvania showed that one-third of Minecraft players learned about the game via Internet videos. In 2010, Minecraft-related videos began to gain influence on YouTube, often made by commentators. The videos usually contain screen-capture footage of the game and voice-overs. Common coverage in the videos includes creations made by players, walkthroughs of various tasks, and parodies of works in popular culture. By May 2012, over four million Minecraft-related YouTube videos had been uploaded. The game would go on to be a prominent fixture within YouTube's gaming scene during the entire 2010s; in 2014, it was the second-most searched term on the entire platform. By 2018, it was still YouTube's biggest game globally. Some popular commentators have received employment at Machinima, a now-defunct gaming video company that owned a highly watched entertainment channel on YouTube. The Yogscast is a British company that regularly produces Minecraft videos; their YouTube channel has attained billions of views, and their panel at Minecon 2011 had the highest attendance. Another well-known YouTube personality is Jordan Maron, known online as CaptainSparklez, who has also created many Minecraft music parodies, including "Revenge", a parody of Usher's "DJ Got Us Fallin' in Love". Minecraft's popularity on YouTube was described by Polygon as quietly dominant, although in 2019, thanks in part to PewDiePie's playthroughs of the game, Minecraft experienced a visible uptick in popularity on the platform. Longer-running series include Far Lands or Bust, dedicated to reaching the obsolete "Far Lands" glitch by foot on an older version of the game. YouTube announced that on 14 December 2021 that the total amount of Minecraft-related views on the website had exceeded one trillion. Minecraft has been referenced by other video games, such as Torchlight II, Team Fortress 2, Borderlands 2, Choplifter HD, Super Meat Boy, The Elder Scrolls V: Skyrim, The Binding of Isaac, The Stanley Parable, and FTL: Faster Than Light. Minecraft is officially represented in downloadable content for the crossover fighter Super Smash Bros. Ultimate, with Steve as a playable character with a moveset including references to building, crafting, and redstone, alongside an Overworld-themed stage. It was also referenced by electronic music artist Deadmau5 in his performances. The game is also referenced heavily in "Informative Murder Porn", the second episode of the seventeenth season of the animated television series South Park. In 2025, A Minecraft Movie was released. It made $313 million in the box office in the first week, a record-breaking opening for a video game adaptation. Minecraft has been noted as a cultural touchstone for Generation Z, as many of the generation's members played the game at a young age. The possible applications of Minecraft have been discussed extensively, especially in the fields of computer-aided design (CAD) and education. In a panel at Minecon 2011, a Swedish developer discussed the possibility of using the game to redesign public buildings and parks, stating that rendering using Minecraft was much more user-friendly for the community, making it easier to envision the functionality of new buildings and parks. In 2012, a member of the Human Dynamics group at the MIT Media Lab, Cody Sumter, said: "Notch hasn't just built a game. He's tricked 40 million people into learning to use a CAD program." Various software has been developed to allow virtual designs to be printed using professional 3D printers or personal printers such as MakerBot and RepRap. In September 2012, Mojang began the Block by Block project in cooperation with UN Habitat to create real-world environments in Minecraft. The project allows young people who live in those environments to participate in designing the changes they would like to see. Using Minecraft, the community has helped reconstruct the areas of concern, and citizens are invited to enter the Minecraft servers and modify their own neighborhood. Carl Manneh, Mojang's managing director, called the game "the perfect tool to facilitate this process", adding "The three-year partnership will support UN-Habitat's Sustainable Urban Development Network to upgrade 300 public spaces by 2016." Mojang signed Minecraft building community, FyreUK, to help render the environments into Minecraft. The first pilot project began in Kibera, one of Nairobi's informal settlements and is in the planning phase. The Block by Block project is based on an earlier initiative started in October 2011, Mina Kvarter (My Block), which gave young people in Swedish communities a tool to visualize how they wanted to change their part of town. According to Manneh, the project was a helpful way to visualize urban planning ideas without necessarily having a training in architecture. The ideas presented by the citizens were a template for political decisions. In April 2014, the Danish Geodata Agency generated all of Denmark in fullscale in Minecraft based on their own geodata. This is possible because Denmark is one of the flattest countries with the highest point at 171 meters (ranking as the country with the 30th smallest elevation span), where the limit in default Minecraft was around 192 meters above in-game sea level when the project was completed. Taking advantage of the game's accessibility where other websites are censored, the non-governmental organization Reporters Without Borders has used an open Minecraft server to create the Uncensored Library, a repository within the game of journalism by authors from countries (including Egypt, Mexico, Russia, Saudi Arabia and Vietnam) who have been censored and arrested, such as Jamal Khashoggi. The neoclassical virtual building was created over about 250 hours by an international team of 24 people. Despite its unpredictable nature, Minecraft speedrunning, where players time themselves from spawning into a new world to reaching The End and defeating the Ender Dragon boss, is popular. Some speedrunners use a combination of mods, external programs, and debug menus, while other runners play the game in a more vanilla or more consistency-oriented way. Minecraft has been used in educational settings through initiatives such as MinecraftEdu, founded in 2011 to make the game affordable and accessible for schools in collaboration with Mojang. MinecraftEdu provided features allowing teachers to monitor student progress, including screenshot submissions as evidence of lesson completion, and by 2012 reported that approximately 250,000 students worldwide had access to the platform. Mojang also developed Minecraft: Education Edition with pre-built lesson plans for up to 30 students in a closed environment. Educators have used Minecraft to teach subjects such as history, language arts, and science through custom-built environments, including reconstructions of historical landmarks and large-scale models of biological structures such as animal cells. The introduction of redstone blocks enabled the construction of functional virtual machines such as a hard drive and an 8-bit computer. Mods have been created to use these mechanics for teaching programming. In 2014, the British Museum announced a project to reproduce its building and exhibits in Minecraft in collaboration with the public. Microsoft and Code.org have offered Minecraft-based tutorials and activities designed to teach programming, reporting by 2018 that more than 85 million children had used their resources. In 2025, the Musée de Minéralogie in Paris held a temporary exhibition titled "Minerals in Minecraft." Following the initial surge in popularity of Minecraft in 2010, other video games were criticised for having various similarities to Minecraft, and some were described as being "clones", often due to a direct inspiration from Minecraft, or a superficial similarity. Examples include Ace of Spades, CastleMiner, CraftWorld, FortressCraft, Terraria, BlockWorld 3D, Total Miner, and Luanti (formerly Minetest). David Frampton, designer of The Blockheads, reported that one failure of his 2D game was the "low resolution pixel art" that too closely resembled the art in Minecraft, which resulted in "some resistance" from fans. A homebrew adaptation of the alpha version of Minecraft for the Nintendo DS, titled DScraft, has been released; it has been noted for its similarity to the original game considering the technical limitations of the system. In response to Microsoft's acquisition of Mojang and their Minecraft IP, various developers announced further clone titles developed specifically for Nintendo's consoles, as they were the only major platforms not to officially receive Minecraft at the time. These clone titles include UCraft (Nexis Games), Cube Life: Island Survival (Cypronia), Discovery (Noowanda), Battleminer (Wobbly Tooth Games), Cube Creator 3D (Big John Games), and Stone Shire (Finger Gun Games). Despite this, the fears of fans were unfounded, with official Minecraft releases on Nintendo consoles eventually resuming. Markus Persson made another similar game, Minicraft, for a Ludum Dare competition in 2011. In 2025, Persson announced through a poll on his X account that he was considering developing a spiritual successor to Minecraft. He later clarified that he was "100% serious", and that he had "basically announced Minecraft 2". Within days, however, Persson cancelled the plans after speaking to his team. In November 2024, artificial intelligence companies Decart and Etched released Oasis, an artificially generated version of Minecraft, as a proof of concept. Every in-game element is completely AI-generated in real time and the model does not store world data, leading to "hallucinations" such as items and blocks appearing that were not there before. In January 2026, indie game developer Unomelon announced that their voxel sandbox game Allumeria would be playable in Steam Next Fest that year. On 10 February, Mojang issued a DMCA takedown of Allumeria on Steam through Valve, alleging the game was infringing on Minecraft's copyright. Some reports suggested that the takedown may have used an automatic AI copyright claiming service. The DMCA was later withdrawn. Minecon was an annual official fan convention dedicated to Minecraft. The first full Minecon was held in November 2011 at the Mandalay Bay Hotel and Casino in Las Vegas. The event included the official launch of Minecraft; keynote speeches, including one by Persson; building and costume contests; Minecraft-themed breakout classes; exhibits by leading gaming and Minecraft-related companies; commemorative merchandise; and autograph and picture times with Mojang employees and well-known contributors from the Minecraft community. In 2016, Minecon was held in-person for the last time, with the following years featuring annual "Minecon Earth" livestreams on minecraft.net and YouTube instead. These livestreams, later rebranded to "Minecraft Live", included the mob/biome votes, and announcements of new game updates. In 2025, "Minecraft Live" became a biannual event as part of Minecraft's changing update schedule.[citation needed] Notes References External links |
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Contents Marcian Hoff Marcian Edward "Ted" Hoff Jr. (born October 28, 1937, in Rochester, New York) is one of the inventors of the microprocessor. Education and work history Hoff received a bachelor's degree in electrical engineering from the Rensselaer Polytechnic Institute in 1958. He applied for his first two patents based on work done for the General Railway Signal Corp. of Rochester, New York during the summers of his undergraduate study. He received a National Science Foundation Fellowship to enroll in Stanford University, where he received his master's degree in 1959 and his Ph.D. in 1962. As part of his Ph.D. dissertation, Hoff co-invented the least mean squares filter and the ADALINE neural network with Bernard Widrow. Hoff joined Intel in 1968 as employee number 12 as "manager of applications research", and is credited with coming up with the idea of using a "universal processor" rather than a variety of custom-designed circuits in the architectural idea and an instruction set formulated with Stanley Mazor in 1969 for the Intel 4004—the chip that started the microprocessor revolution in the early 1970s. Development of the silicon-gate design methodology and the actual chip design was done by Federico Faggin, who also led the project during 1970-1971. Masatoshi Shima from Busicom defined the logic. In 1975 he started a group to work on large-scale integration for use in the telephone industry, resulting in various commercial products: first commercial monolithic telephone (named "CODEC"), first commercial switched-capacitor filter (for use with CODEC), a microprocessor for real-time digitizing analog signals (Intel 2920), and speech recognition hardware. In 1980, Hoff was named the first Intel Fellow, which is the highest technical position in the company. He stayed in that position until 1983 when he left for Atari. After the video game crash of 1983, Atari was sold in 1984, and Hoff became an independent consultant. He then joined Teklicon in 1986 as an agent, and since 1990 as an employee. Popular culture Hoff was featured in an Intel advertisement, calling him the "rock star" of Intel and comparing him to the rock stars of American culture. Awards In 1954, he was one of the Westinghouse Science Talent Search (now Intel STS) finalists. He was awarded the Stuart Ballantine Medal in 1979, the IEEE Cledo Brunetti Award in 1980, and the Franklin Institute Certificate of Merit in 1996. Hoff was awarded the Stibitz-Wilson Award from the American Computer & Robotics Museum in 1997. He was inducted into the National Inventors Hall of Fame in 1996 and received the National Medal of Technology and Innovation in 2009 from President Barack Obama. He was made a Fellow of the Computer History Museum in 2009 "for his work as part of the team that developed the Intel 4004, the world's first commercial microprocessor." He received the 2011 IEEE/RSE Wolfson James Clerk Maxwell Award. References |
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[SOURCE: https://en.wikipedia.org/wiki/Aylo] | [TOKENS: 5163] |
Contents Aylo Aylo is a Canadian multinational pornographic conglomerate owned by Canadian private equity firm Ethical Capital Partners. It is primarily involved in internet pornography, operating a number of video sharing websites (including platforms such as Pornhub, RedTube, Tube8, and YouPorn), and pornographic film studios such as Brazzers, Digital Playground, Men.com, Reality Kings, Sean Cody, and WhyNotBi.com, among others. Aylo's headquarters are located in Montreal, Quebec, Canada, but the company's corporate structure is divided among entities domiciled in a number of other countries (including tax havens such as Curaçao and Luxembourg). The company is one of the largest distributors of online pornography, to the extent that it has been accused of having a monopoly position (with 3 out of the 10 most popular online pornography sites being owned by the company). In 2013, a spokesperson for the company stated that its properties were among the top five users of internet bandwidth in the world. The company has been subject to a number of lawsuits and filed litigation against its competitors. They were sued in California for hosting non-consensual pornography produced by GirlsDoPorn, which coerced women into appearing in their videos under false pretenses. In January 2021, a class action lawsuit making similar claims was launched in Montreal for anyone who had pornography photos and videos, some of which may have been taken when they were underage, shared on its websites without their consent, since 2007. The lawsuit stated that the company knowingly did not "investigate or question its business partner regarding the mounting evidence of sex trafficking". In February 2021, a U.S.-based civil class action lawsuit was launched against the company on behalf of child sex trafficking victims whose child sexual abuse material was uploaded to Pornhub. On 21 December 2023, Aylo agreed to pay a fine of $1.8 million plus additional compensation to GirlsDoPorn victims, and to have an independent party assess their content moderation processes for three years. History In the late 1990s, German Fabian Thylmann created NATS (Next-Generation Affiliate Tracking Software), which was used for marketing pornography across different websites. Mansef was funded by Concordia University graduates Stephane Manos and Ouissam Youssef (Mansef a portmanteau of the two's surnames) in 2004 as the holding company for various "thumbnail gallery post" websites and an affiliate network. It later launched Brazzers and a porn production company among various other pay sites. In 2006, Thylmann sold his shares in the company that controlled NATS and used the proceeds to purchase the Privat Amateure website. Matt Keezer started Pornhub in 2007 under Interhub in which Mansef was also a partner. Mansef was run as a familial business with several of the company managers being related to each other; Manos, Youssef and Keezer later wanted to sell the companies, looking to move onto other ventures. Between 2006 and 2010, Thylmann bought three more websites: MyDirtyHobby, Webcams, and Xtube. The domain name manwin.com was first registered in August 2007. In March 2010, Thylmann bought the assets of Mansef and Interhub, and merged the properties into a new entity called Manwin. Thylmann also bought WebCams.com in a separate deal during the same period. Manwin went on an acquisition spree of other popular pornographic entities. In June 2010, Manwin opened non-adult video sharing website Videobash.com (now defunct). In September 2010, Manwin acquired EuroRevenue, which owned various niche pornography sites. In November 2010, Manwin introduced celebrity news website Celebs.com (now defunct). In December 2010, Manwin entered into a partnership with Wicked Pictures to manage Wicked Pictures' paysites. The 2010 Manwin purchases accounted for US$130 million in debt. In 2011, the company raised US$362 million in financing from 125 secret investors, including Fortress Investment Group, JPMorgan Chase, and Cornell University. In May 2011, Manwin acquired the pornographic video sharing website YouPorn. In June 2011, Manwin bought all adult related assets of Carsed Marketing Incorporated, including Twistys, Twistys Cash Affiliate Program, GayTube, SexTube, and TrannyTube. Manwin also created 3DXSTAR in a partnership with Funky Monkey Productions. In November 2011, Manwin became an operating partner of Playboy, managing the brand's online and entertainment business Playboy Plus Entertainment, which operates a number of television channels and online services based in the UK and Benelux. Manwin also launched Legendary Stats, a service that aggregates multiple affiliate programs and is targeted at affiliate site operators with large traffic volumes. In January 2012, Manwin signed a deal to acquire the assets of the American pornographic movie studio Digital Playground. In April 2012, Manwin and Miami-based RK Netmedia Inc. filed a merger notification jointly authorized by Manwin and Reality Kings with the Austrian Federal Competition Authority. In September 2012, Manwin completed the acquisition. Company documents show that following the deal in the autumn, RK Holdings gave a Dublin company, Manwin Content RK, the right to use thousands of its pornography movies. In June 2012, Manwin launched Babes.com for its "glamcore" network. In March 2013, MindGeek's co-owner Feras Antoon and his brother Mark Antoon were cited alongside the CEO of gaming technology giant Amaya Inc. and various of its own senior officers and stakeholders. The Quebec Market Authority, the province's market regulator that is somewhat equivalent to the U.S. SEC, investigated Amaya's executives for trading on privileged information. According to the charges, some MindGeek executives were found to have benefited from the leak of information, although they were not major players in the insider trading ring. In July 2013, Manwin filed a merger notification with the Austrian Competition Authority to acquire RedTube.com. During the summer of 2013, Manwin / MindGeek acquired all of RedTube properties from Hong Kong–based Bright Imperial Ltd. for an undisclosed sum. In December 2013, the domain name RedTube8.xxx was also transferred to MindGeek after a trademark dispute. In October 2013, Thylmann sold his stake in Manwin, after facing tax evasion charges, to the senior management of the company, composed of Feras Antoon and David Tassilo, for $100 million, and later in the same month the company's name was changed to MindGeek. This took place as Manwin and RedTube, a large porn tube site not in its network, merged. Playboy CEO Scott Flanders described the 2011 partnership with MindGeek as "the biggest mistake I've made at the company," saying that "Playboy should not have association with being in the sex-act business." In the spring of 2014, Playboy took back control of Playboy.com "at significant expense", although MindGeek still retained control of Playboy TV and Playboy Plus, and MindGeek still owns the Spice Networks TV channels, which were also bought from Playboy. In December 2014, MindGeek announced they had signed a deal to manage the online assets of Really Useful Ltd., some of which include the websites BDSM.xxx, Casting.xxx, Czech.xxx, DaneJones.com, Fake Taxi, Lesbea.com, MassageRooms.com, Mature.xxx, Mom.xxx, Orgasms.xxx, PublicAgent.com, PublicSex.xxx, Teen.xxx, and Tubes.xxx. In April 2015, Playboy Plus and M7 Group formed a partnership to launch Reality Kings TV in Benelux and Central and Eastern Europe on satellite TV services. In May 2015, MindGeek signed a distribution deal with Pulse Distribution, one of the largest distributors of adult entertainment, to distribute content from MindGeek's movie studios, including content from Brazzers and Digital Playground, and DVDs from Babes.com, Men.com, Mofos and Reality Kings. In October 2015, MindGeek acquired ExtremeTube, SpankWire, KeezMovies. These sites are interlinked in network called Spankwire Sites in similar fashion as the Pornhub Network. In April 2018, MindGeek started accepting the Verge cryptocurrency as payment for their various services. In December 2020, a Financial Times exposé was published, listing Bernd Bergmair as the main owner of MindGeek. In June 2022, the company confirmed the resignation of its CEO, Feras Antoon, and its COO, David Tassillo. On 16 March 2023, MindGeek was acquired by Ethical Capital Partners, an Ottawa-based private equity firm. This acquisition came a day after Netflix debuted the documentary Money Shot: The Pornhub Story, which looks at the controversies involving Pornhub. In August 2023, MindGeek announced it was rebranding as Aylo; the company stated that the rebranding "comes in response to the need for a fresh start and a renewed commitment to innovation, diverse and inclusive adult content, and trust and safety." Corporate structure Aylo operates under a complex structure of multiple companies in countries such as the British Virgin Islands, Canada, Curaçao, Cyprus, Germany, Ireland, Luxembourg, Mauritius, the Netherlands, the United Kingdom, and the United States. Its structure has been described as mostly a way to avoid corporate tax by a de facto Canadian company; with billing companies in Ireland, subsidiaries in Curaçao and holding ones in Cyprus and Luxembourg, all countries that have been identified as tax havens or having lax tax regulations. Canada also has special tax treaties with Luxembourg, the legal headquarters of Aylo, where a Canadian subsidiary is exempt from taxes paid on royalties to its Luxembourg parent. Most employees work at the headquarters in Montreal on Décarie Boulevard, where more than 1,000 are employed. Adult industry In 2013, the adult industry news website XBIZ described MindGeek as "the largest adult entertainment operator globally", and a spokesperson from Manwin, who spoke to the Irish Independent newspaper in 2013, stated that they are "one of the top five bandwidth consumption companies in the world". The Internet pornography review site TheBestPorn.com lists 164 pornographic membership sites that are owned or represented by MindGeek. It has been reported that MindGeek's dominance in online pornography may have negative results because of the monopolistic powers they have from owning both production and distribution avenues. The "Pornhub Network" is a group of pornographic video sharing websites operated by Aylo, which includes GayTube, Peeperz, PornIQ (launched by Pornhub), Pornhub, RedTube, YouPorn, Tube8, and Thumbzilla. The network also operates PornMD, a video search engine that aggregates content from across the group. In March 2013 PornMD launched an interactive map which allows users to view the top 10 searches on PornMD for any selected country, and in February 2014 they introduced a live feed which shows search terms inputted by users in real time. The three highest-ranked sites in the Pornhub Network are Pornhub, RedTube and YouPorn. In November 2013, it was reported that Pornhub has over 1 billion visitors per month, and a December 2014 article in Adweek states that Pornhub has 50 million daily visitors. Pornhub.com scores at Alexa Global Rank 27 (as of 18 March 2019). Pornhub has been criticized for hosting non-consensual pornography, with some victims reporting that Pornhub failed to act or acted slowly or ineffectively when pointed to the videos of them. They were also criticized for their partnership with GirlsDoPorn and failure to remove their videos from the website after sex trafficking charges against the company were filed. After significant backlash, on 14 December 2020, Pornhub removed all non-verified videos on their platform. TrafficEstimate.com said that Redtube.com generates over 90 million visits per month, while YouPorn.com had almost 80 million visits per month (based on the data for 30 days up to mid-November 2014. Data for Pornhub.com was not available from TrafficEstimate). YouPorn claim that their partner program has 400 content providers who participate. In August 2023, as part of the Pornhub network, Aylo launched UViU, a platform for creators to sell content directly to fans. Designed with creator input, UViU helps diversify income and increase earnings. It offers tools for video sales, paid subscriptions, tips, and direct messages. Fans can discover and browse creators’ content, while creators can manage their Pornhub and UViU accounts from one dashboard. As of 2014[update], MindGeek's mobile pornography websites handled millions of visits each day in North America; they were awarded the "Future Mobile Award for Mobile Adult Services" by Juniper Research in 2012. MindGeek owns the pornographic movie studios Babes.com, Brazzers, Digital Playground, Reality Kings, Sean Cody, Twistys, Mofos.com and Men.com, they manage the websites of Wicked Pictures, and Really Useful Ltd., and they established 3DXSTAR in partnership with Funky Monkey Productions. Mindgeek also manage Playboy's online and television operations (although they no longer manage Playboy.com. See history section above). In January 2014, a Mindgeek official stated that they were developing an Android app for Google's Chromecast digital media player, along with an app for Panasonic smart TVs, that would enable streaming of Playboy.tv content. The plan to release a Chromecast app was shown to be unfeasible in February 2014, when Google originally revealed their terms of service for Chromecast app developers, which stated that "We don't allow content that contains nudity, graphic sex acts, or sexually explicit material." In November 2012, Manwin was the biggest funder of the No on Government Waste Committee. The committee ran the No on Measure B campaign, against a proposed law to require the use of condoms in all vaginal and anal sex scenes in pornography productions filmed in Los Angeles County, California. The No on Measure B campaign was supported by the Los Angeles County Federation of Republican Women, the Los Angeles County Republican and Libertarian Parties, the Valley Industry & Commerce Association (VICA), and the Log Cabin Republicans of Los Angeles. Advertising Aylo owns TrafficJunky, an online advertising network that operates across its properties. The vice president of Pornhub, Corey Price commented in December 2014 that Pornhub wants to make watching porn "something that's acceptable to talk about", which would be likely to benefit Pornhub, since according to Price "it's still taboo [to advertise on X-rated sites like Pornhub]". In October 2013, the media and marketing publication Digiday reported that Pornhub has already shown advertisements for various mainstream products on the Pornhub web site, including advertisements for movies, musical acts, anti-virus software, and a food delivery service, although most advertisements were still adult-related. In mid-March 2023, it was reported that the Russian private military company Wagner Group had purchased recruitment advertising on the network, which was later pulled by Pornhub due to its political nature. In April 2013, security researcher Conrad Longmore, who writes a blog on malware, spam and scams, published a report on the serving of malvertising by third-party advertisers on internet pornography websites. Longmore's figures were collected using Google Safe Browsing Diagnostics, which looks for harmful content on websites, and the statistics for two sites; xHamster and Pornhub were published by BBC News. The BBC article stated that based on Longmore's research, 5% of pages on xHamster (which has never been owned by Manwin), and 12.7% of pages on Pornhub incorporated malvertising. Manwin said in a statement that their own figures showed that 0.003% of the advertisements they served over the period that Longmore's data was collected contained malware, and they said that the advertisements they serve are monitored for malware and malware is immediately removed. In July 2013, Manwin announced an agreement with security vendor RiskIQ to provide security monitoring for ads served by TrafficJunky, including proactive monitoring for malware before and after they go live. Age controls and child protection Many US states have passed legislation requiring pornographic websites to verify that their users are aged over 18, or else be vulnerable to civil lawsuits. In response Aylo has ceased operating in those states, saying that it cannot comply with the laws without violating its users' privacy. Aylo has been a Platinum Sponsor of the Association of Sites Advocating Child Protection (ASACP) since 2011. ASACP is an American non-profit organization that fights against child pornography and aims to enhance the effectiveness of parental content filtering technology through the provision of the RTA ("Restricted to Adults") label, which can be implemented by webmasters of adult sites. In March 2014 the UK video-on-demand co-regulator ATVOD requested a change in the law so that credit and debit card operators would be forbidden from processing payments from British customers of pornographic websites that did not carry out age checks before granting access. MindGeek responded in a statement: "The best solution lies in a multi-layered approach in which the parent assumes the central role." The UK's Conservative Party won the country's 2015 general election with a pledge to obligate UK internet service providers to block access to hardcore pornographic websites that did not implement age restrictions by using verifiable age checks. In light of this MindGeek joined talks in May 2015 with the Digital Policy Alliance (DPA), an organization that is funded by digital technology companies and informs members of parliament in the UK and the EU on policy issues that affect online and digital technologies. The DPA has a working group to create age verification methods that could be used to comply with such laws. The Digital Economy Act 2017 introduced the relevant legislation, and in March 2018 MindGeek announced that its AgeID age-verification tool, which has been in use in Germany since 2015, would be made available in the UK in time for the proposed introduction of compulsory age-verification in April 2018. It was intended that the software would be made commercially available to all pornographic websites accessible within the UK, and offered free to independent UK studios, producers and bloggers. The software uses "third-party age-verification companies" to authenticate the age of those who register, after which they are able to access multiple sites across multiple devices without logging in again. MindGeek was one of the leading private companies competing to provide an age-verification solution for the British Board of Film Classification, the organization designated as responsible for the age-verification process. The implementation date was originally April 2018 but was delayed allowing time for public consultation, and never implemented. The part of the Act requiring age verification was eventually repealed by the Online Safety Act 2023. In May 2018 the Open Rights Group, a UK-based digital rights campaigning organization, criticized MindGeek's record on data security and commented: "Allowing pornographic sites to own and operate age verification tools leads to a conflict of interest between the privacy interests of the user, and the data mining and market interests of the company." In October 2019 the UK government abandoned their existing plans, instead proposing the introduction of an alternative regulatory system for the Internet. Lawsuits Manwin Licensing and Digital Playground filed an antitrust lawsuit in California in November 2011, against ICANN and ICM Registry over the introduction of the .xxx TLD. Amongst their allegations, Manwin claimed that in introducing the new suffix, ICANN and ICM registry had exploited the market by making domain registrations expensive with no price caps in place, and created a need for defensive domain registrations with no provision for companies to block typos of their trademarks. Manwin announced that it would not allow its content to be used on any sites with the suffix, with Fabian Thylmann, who was then managing partner of Manwin saying: "We oppose the .XXX domain and all it stands for. It is my opinion that .XXX domain is an anticompetitive business practice that works a disservice to all companies that do business on the Internet." In September 2012, ICM filed a counterclaim for $120 million against Manwin Licensing International. Part of the 24-page long claim alleged: "Manwin, Digital Playground, and their related companies, affiliates, brands, and certain third-party affiliates have conspired to boycott the .XXX TLD and have coerced and/or encouraged the boycott of .XXX websites by third parties." All of ICM's counterclaims were dismissed in the second half of February 2013. The judge in the case stated: "Harm to ICM only is not sufficient to constitute antitrust injury. It must allege harm to the competitive process." In May 2013, Manwin agreed to settle the antitrust lawsuit it brought against ICM Registry over the cost of .xxx web domain names. The settlement will result in discounted wholesale prices of $7.85 a year for .xxx names during May 2013, and similar offers in the future. ICM Registry is owned by British former fax-machine mogul Stuart Lawley. The settlement provides that ICM will not pay any money directly to MindGeek.[citation needed] In May 2013, ExitExchange Corp. sued Manwin USA Inc. in Texas, alleging that its patent for pop-under advertisements had been infringed by Tube8.com and Pornhub.com. In July 2013, Manwin was sued by John Mikkelson and Robert Freidson, the operators of Skky Inc., in Minneapolis over the alleged infringement of a patent that describes a method for delivering compressed audio and images on mobile devices. In October 2014, MindGeek USA Inc. was sued by Preservation Technologies LLC in Delaware for alleged infringement on 19 different sites operated by Mindgeek of 11 patent components on data distribution and communication systems, such as a system for cataloging and retrieving videos and other media associated with keywords. The case was withdrawn in March 2015, after Mindgeek came to a settlement deal with Preservation Technologies LLC. In December 2020, MindGeek was sued in California for hosting non-consensual pornography produced by GirlsDoPorn, which coerced women into appearing in their videos under false pretenses. The forty plaintiffs sought $80 million in damages including distress, ostracization, trauma and attempted suicide. The lawsuit claims that MindGeek knew about the company's sex trafficking as early as 2009 and definitely by fall 2016, but continued to partner with GirlsDoPorn until the company became defunct. MindGeek featured GirlsDoPorn as a Content Partner and a member of the Viewshare Program. The lawsuit also alleges that MindGeek failed to remove GirlsDoPorn videos despite requests for removal by victims, as recently as December 2020. Another ten women joined the lawsuit, which was settled in October 2021 under undisclosed terms. In January 2021, a class action lawsuit making similar claims was launched in Montreal. The Canadian proposed class action sought $600 million for anyone who had pornography photos and videos, some of which may have been taken when they were underage, shared on MindGeek's sites without their consent, since 2007. The lawsuit stated that MindGeek knowingly did not "investigate or question its business partner regarding the mounting evidence of sex trafficking". On 21 December 2023, Aylo agreed to pay a fine of $1.8 million plus additional compensation to GirlsDoPorn victims, and to have an independent party assess their content moderation processes for three years. In February 2021, a civil class action lawsuit against MindGeek was launched in Alabama and it leveled claims against MindGeek/Pornhub on behalf of child sex trafficking victims. The lawsuit laid out arguments regarding the way child sexual abuse material (CSAM) of the plaintiffs was uploaded to and monetized by Pornhub. The attorneys bringing the suit included lawyers working for the National Center on Sexual Exploitation. In a ruling issued on 29 July 2022, U.S. District Judge Cormac Carney ruled that it was reasonable to conclude that MindGeek's activity in hosting child pornography was knowingly facilitated by Visa. The judge ruled in favor of the plaintiff Serena Fleites, and denied Visa's motion to dismiss the case. In August 2022, in the immediate aftermath of the decision, Mastercard and Visa jointly suspended their acceptance of payments from TrafficJunky. See also References Further reading External links 45°29′50.0″N 73°39′23.4″W / 45.497222°N 73.656500°W / 45.497222; -73.656500 |
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[SOURCE: https://en.wikipedia.org/wiki/Stanley_Mazor] | [TOKENS: 842] |
Contents Stanley Mazor Stanley Mazor is an American microelectronics engineer. He is one of the co-inventors of the world's first microprocessor architecture, the Intel 4004, together with Ted Hoff, Masatoshi Shima, and Federico Faggin. Early years As a youth, Mazor's family moved to California, where he attended Oakland High School from which he graduated in 1959. He enrolled in San Francisco State University (SFSU), majoring in math and studying helicopter design and construction as a hobby. Mazor met his future wife Maurine at SFSU and they wed in 1962. Around the same time, he became interested in computers and learned to program SFSU's IBM 1620 computer, taking a position as a professor's assistant and teaching other students to use the technology. Meanwhile, he continued to study computer architecture in technical manuals outside of school. Career summary In 1964, he became a programmer with Fairchild Semiconductor, followed by a position as computer designer in the Digital Research Department, where he co-patented "Symbol", a high-level language computer. (The "Symbol" computer was never patented as a complete unit, and the U.S. Patent Office lists only four patented sub-units: 3,643,225: Memory Control System; 3,643,227: Job Flow and Multiprocessor Operation Control System; 3,577,130: Means for Limiting Field Length of Computed Data; and 3,647,348: Hardware-Oriented Paging Control System. Mazor's name is on that last one.) In 1969, he joined the year-old Intel Corporation, and was soon assigned to work with Ted Hoff on a project to help define the architecture of a microprocessor—often dubbed a "computer-on-a-chip"—based on a concept developed earlier by Hoff. The Japanese calculator manufacturer Busicom asked Intel to complete the design and manufacture of a new set of chips. Credited along with Faggin, Hoff, and Masatoshi Shima of Busicom as co-inventor, Mazor helped define the architecture and the instruction set for the revolutionary new chip, dubbed the Intel 4004. Although there was an initial reluctance on the part of Intel marketing to undertake the support and sale of these products to general customers, Hoff and Mazor joined Faggin, designer of the 4004 and project leader, and actively campaigned for their announcement to the industry and helped define a support strategy that the company could accept. Intel finally announced the 4004 in 1971. After working as a computer designer for six years, Mazor moved to Brussels, Belgium where he continued to work for Intel, now as an application engineer helping customers to use the company's products. He returned to California the following year, and began teaching, first in Intel's Technical Training group, and later at Stanford University and the University of Santa Clara. Various teaching engagements took him around the world, including Stellenbosch, South Africa; Stockholm, Sweden; and Nanjing, China. In 1984, Mazor joined Silicon Compiler Systems. In 2008, Mazor was the Training Director of BEA Systems. Publications In 1993, then working at Synopsys, he coauthored, with Patricia Langstraat, a book on chip design language entitled A Guide to VHDL. Over the course of his career, Mazor has also published fifty articles. Recognition Along with his co-inventors Hoff, Faggin, and Shima, he has received numerous awards and recognitions, including the Ron Brown American Innovator Award, the 1997 Kyoto Prize, and induction into the National Inventors Hall of Fame. In 2009 the four were inducted as Fellows of the Computer History Museum "for their work as the team that developed the Intel 4004, the world's first commercial microprocessor." In 2010, Mazor and his co-inventors Hoff and Faggin, were awarded the National Medal of Technology by President Barack Obama. References External links |
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[SOURCE: https://en.wikipedia.org/wiki/Feed_(Facebook)] | [TOKENS: 1931] |
Contents Feed (Facebook) Facebook's Feed, formerly known as the News Feed, is a web feed feature of the social networking service. The feed is the primary system through which users are exposed to content posted on the network. Feed highlights information that includes profile changes, upcoming events, and birthdays, among other updates. Using a proprietary method, Facebook selects a handful of updates to show users every time they visit their feed, out of an average of 2,000 updates they can potentially receive. Over two billion people use Facebook every month, making the network's Feed the most viewed and most influential aspect of the news industry. The feature, introduced in 2006, was renamed "Feed" in 2022. History Before 2006, Facebook simply consisted of profiles, requiring the user to visit a profile to see any new posts. On September 6, 2006, Facebook announced a new home page feature called "News Feed". The new layout created an alternative home page in which users saw a constantly updated list of their friends' Facebook activities. Initially, the addition of the News Feed caused discontent among Facebook users, many of whom complained that the feed was too intrusive, detailing every moment with timestamps, and violating their privacy. Some called for a boycott of the company. In response to this dissatisfaction, CEO Mark Zuckerberg issued a statement clarifying that "We didn't take away any privacy options." Following this, Zuckerberg later issued an open letter apologizing for a lack of information on new features and users' controls, writing that "We really messed this one up. [...] I'd like to try to correct those errors now." The News Feed has received multiple updates over the years since its original setup. In 2008, Facebook added a feedback button to each story in a user's feed, letting them tell the service about their personal preferences for their feed. However, the feedback button was removed in April, and returned in July, with Facebook reportedly removing the first iteration of the feedback options due to a low impact on user satisfaction compared to other aspects of the algorithm. In March 2009, Facebook rolled out the option to "Like" a page to see updates from it in their feed, gave users customizable filters to determine what friends they wanted to see News Feed updates from, and also added a publishing field at the top of the feed, previously exclusive to user profiles, for easy post creation. The publishing field contained the text "What's on your mind?", a similar but also notably different question from Twitter's "What are you doing right now?" A few weeks later, the company introduced controls to reduce content from app interactions, and enabled the feed to show photos in which friends were tagged. In December 2010, Facebook rolled out a new drop-down button, offering users the ability to view News Feed by categories, including only games, status updates, photos, links, Pages, or specific groups of people. In February 2011, Facebook added News Feed settings to let users specify if they want content from only the people and pages they interact with the most, rather than everyone. In September, Facebook updated the feed to show top stories and most recent stories, rather than relying on a strictly chronological order. Later the same year, it introduced the "ticker", a real-time extension of News Feed, located on the right side of the screen. At the end of the year, news outlets reported that Facebook would be starting allowing advertisements through "Sponsored Stories" in News Feed for the first time. Advertisements started rolling out on January 10, 2012, with a "Featured" tag declaring its paid status. Advertisements were expanded to mobile in February 2012. In March 2013, Facebook held a press event to unveil new updates to News Feed, including a more minimalistic design with consistency across both the website and mobile devices. This included a new layout for posts, presenting friends' photos, shared articles, and maps with larger text and images, and brands' logos. New "sub-feeds" show updates in specific areas, such as posts from specific friends or interest updates. However, the initial limited rollout of the new design saw a trend of lower user engagement, prompting the company to stop the rollout. A year later, in March 2014, Facebook once again updated its News Feed, but in response to criticism from users, the company chose to scale back its efforts. While bringing bigger photos that span the width of the feed, font changes, and design tweaks to buttons and icons, the new design removed the drop-down menu, placing relevant entries in a navigation on the left side of the screen while removing some of the sub-feeds. It also simplified the comments system, altered the appearance of profile photos in the feed, and added a search bar at the top of the page. News Feed product manager Greg Marra explained that "People don't like us moving their furniture around, because you break muscle memory". Marra also stated that "Over the last year, we've spent a lot of time seeing what people were saying, what was working, what wasn't working, and we're rolling out the version that takes all of that feedback into account". In January 2018, following a difficult 2017, marked by accusations of relaying fake news and revelations about groups close to Russia which tried to influence the 2016 US presidential election (see Russian interference in the 2016 United States elections) via advertisements on his service, Mark Zuckerberg announced in his traditional January post: We're making a major change to how we build Facebook. I'm changing the goal I give our product teams from focusing on helping you find relevant content to helping you have more meaningful social interactions — Mark Zuckerberg Following surveys of Facebook users, this desire for change will take the form of a reconfiguration of the News Feed algorithms in order to: These changes are expected to improve "the amount of meaningful content viewed". However, a 2022 study shows that when news content is removed from the Feed, "many users will find almost nothing of value". In 2022, Facebook's parent company, Meta Platforms, announced it is renaming the "News Feed" to simply be named "Feed". Influence Approximately two billion people use the Facebook platform every month. Approximately 62 percent of adults in the United States use social media to get news, meaning Facebook's influence has become a liability for the company. During the 2016 U.S. presidential election, the Russian government used the Facebook platform to disseminate fake news that more frequently favored Donald Trump over Hillary Clinton. As a social media platform, user-generated content and media created content can be shared vastly within the digital community. This has come with repercussions for Facebook, as they were accused of releasing personally identifiable information of approximately 82 million users to Cambridge Analytica. The Cambridge Analytica Scandal drew much attention to the privacy settings and influence of the Feed on the Facebook platform. The Feed has become a significant contributor to the spread of misinformation; as former U.S. president Barack Obama put it, "misinformation...looks the same when you see it on a Facebook page or you turn on your television." After the 2016 election, journalist Margaret Sullivan called on Facebook inc. to hire an editor to monitor the News Feed to ensure accuracy and balance of news stories. In late 2016, Facebook described plans to issue warning labels on certain News Feed posts. Facebook has a partnership with fact-checkers like Snopes.com and PolitiFact, and would display that a story is disputed if it has been debunked by one of those fact-checkers. Operation On the Facebook app, Feed is the first screen to appear, partially leading most users to think of the feed as Facebook itself. The Facebook Feed operates as a revolving door of articles, pages the user has liked, status updates, app activity, likes from other users photos and videos. This operates an arena of social discussion. Algorithms are employed on the Facebook platform to curate a personalized experience for users that is predominantly featured in the Feed. Adam Mosseri is Facebook's vice president in charge of Feed and Chief Product Officer while Chris Cox runs the Facebook app and Feed. On October 1, 2018, it was announced Adam Mosseri would become the head of Instagram. Facebook's proprietary recommendation algorithms compare the merits of about 2,000 potential posts every time the app is opened, using a complex system based on providing a meaningful experience, over that of clicks, reactions, or reading time. The Feed has been described as a filter bubble, showing users personalized results about information deemed interesting to them, in contrary to showing all information, even information that they disagree with. Subsequently, the functionality of the Feed has been debated as to whether or not it is an echo-chamber. Facebook has been researching this situation since 2010, and initially used an algorithm known as EdgeRank. By late 2013, clickbait articles had become significantly prevalent, leading Facebook's chief product officer Chris Cox's team to hire survey panels to assess how Feed was working. As a result, Facebook began adding ever-increasing numbers of data points to its algorithm to significantly reduce clickbait. Effect on opinion A 2015 study published in Science concluded that Facebook's algorithms had a minimal effect on the news feed's diversity, though the study prompted academic criticism. Researchers at the MIT Media Lab Center for Civic Media produced an application called Gobo which allows users to see the results of adjusting the algorithm. See also References |
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[SOURCE: https://en.wikipedia.org/wiki/Last_man_standing_(video_games)] | [TOKENS: 294] |
Contents Last man standing (video games) Last man standing (LMS), last one standing (LOS), or last team standing (LTS) is a multiplayer deathmatch gameplay mode featured in certain computer and video games, particularly, but not exclusively, first-person shooters, and is also the basis of battle royale games. The aim of a player in a last-one-standing match is to neutralize their opponents and remain the sole survivor. The basic rules followed are generally the same as a regular deathmatch mode, with one important difference being that respawn is limited or not allowed at all. Each player is assigned a specific number of lives per match (or just one when there is no respawn). Once these lives have been expended, the player is no longer able to return to the current match and remains as an invisible spectator until there is a winner and the LOS round is over. In some games, the player is allowed to buy or pick up items before spawning, while other titles have the player spawn with full weapons and ammo and there are no powerups available on the map. Several different variations of the last man standing mode exist, with the most common being team LOS. The rules are the same as the standard LOS, the winning team being the one that eliminates all members of the opposing teams while keeping at least one of its members alive. The first last-one-standing video game with a shrinking play zone was the 1983 action game Bomberman. See also References |
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[SOURCE: https://en.wikipedia.org/wiki/Social_network#cite_note-43] | [TOKENS: 5247] |
Contents Social network 1800s: Martineau · Tocqueville · Marx · Spencer · Le Bon · Ward · Pareto · Tönnies · Veblen · Simmel · Durkheim · Addams · Mead · Weber · Du Bois · Mannheim · Elias A social network is a social structure consisting of a set of social actors (such as individuals or organizations), networks of dyadic ties, and other social interactions between actors. The social network perspective provides a set of methods for analyzing the structure of whole social entities along with a variety of theories explaining the patterns observed in these structures. The study of these structures uses social network analysis to identify local and global patterns, locate influential entities, and examine dynamics of networks. For instance, social network analysis has been used in studying the spread of misinformation on social media platforms or analyzing the influence of key figures in social networks. Social networks and the analysis of them is an inherently interdisciplinary academic field which emerged from social psychology, sociology, statistics, and graph theory. Georg Simmel authored early structural theories in sociology emphasizing the dynamics of triads and "web of group affiliations". Jacob Moreno is credited with developing the first sociograms in the 1930s to study interpersonal relationships. These approaches were mathematically formalized in the 1950s and theories and methods of social networks became pervasive in the social and behavioral sciences by the 1980s. Social network analysis is now one of the major paradigms in contemporary sociology, and is also employed in a number of other social and formal sciences. Together with other complex networks, it forms part of the nascent field of network science. Overview The social network is a theoretical construct useful in the social sciences to study relationships between individuals, groups, organizations, or even entire societies (social units, see differentiation). The term is used to describe a social structure determined by such interactions. The ties through which any given social unit connects represent the convergence of the various social contacts of that unit. This theoretical approach is, necessarily, relational. An axiom of the social network approach to understanding social interaction is that social phenomena should be primarily conceived and investigated through the properties of relations between and within units, instead of the properties of these units themselves. Thus, one common criticism of social network theory is that individual agency is often ignored although this may not be the case in practice (see agent-based modeling). Precisely because many different types of relations, singular or in combination, form these network configurations, network analytics are useful to a broad range of research enterprises. In social science, these fields of study include, but are not limited to anthropology, biology, communication studies, economics, geography, information science, organizational studies, social psychology, sociology, and sociolinguistics. History In the late 1890s, both Émile Durkheim and Ferdinand Tönnies foreshadowed the idea of social networks in their theories and research of social groups. Tönnies argued that social groups can exist as personal and direct social ties that either link individuals who share values and belief (Gemeinschaft, German, commonly translated as "community") or impersonal, formal, and instrumental social links (Gesellschaft, German, commonly translated as "society"). Durkheim gave a non-individualistic explanation of social facts, arguing that social phenomena arise when interacting individuals constitute a reality that can no longer be accounted for in terms of the properties of individual actors. Georg Simmel, writing at the turn of the twentieth century, pointed to the nature of networks and the effect of network size on interaction and examined the likelihood of interaction in loosely knit networks rather than groups. Major developments in the field can be seen in the 1930s by several groups in psychology, anthropology, and mathematics working independently. In psychology, in the 1930s, Jacob L. Moreno began systematic recording and analysis of social interaction in small groups, especially classrooms and work groups (see sociometry). In anthropology, the foundation for social network theory is the theoretical and ethnographic work of Bronislaw Malinowski, Alfred Radcliffe-Brown, and Claude Lévi-Strauss. A group of social anthropologists associated with Max Gluckman and the Manchester School, including John A. Barnes, J. Clyde Mitchell and Elizabeth Bott Spillius, often are credited with performing some of the first fieldwork from which network analyses were performed, investigating community networks in southern Africa, India and the United Kingdom. Concomitantly, British anthropologist S. F. Nadel codified a theory of social structure that was influential in later network analysis. In sociology, the early (1930s) work of Talcott Parsons set the stage for taking a relational approach to understanding social structure. Later, drawing upon Parsons' theory, the work of sociologist Peter Blau provides a strong impetus for analyzing the relational ties of social units with his work on social exchange theory. By the 1970s, a growing number of scholars worked to combine the different tracks and traditions. One group consisted of sociologist Harrison White and his students at the Harvard University Department of Social Relations. Also independently active in the Harvard Social Relations department at the time were Charles Tilly, who focused on networks in political and community sociology and social movements, and Stanley Milgram, who developed the "six degrees of separation" thesis. Mark Granovetter and Barry Wellman are among the former students of White who elaborated and championed the analysis of social networks. Beginning in the late 1990s, social network analysis experienced work by sociologists, political scientists, and physicists such as Duncan J. Watts, Albert-László Barabási, Peter Bearman, Nicholas A. Christakis, James H. Fowler, and others, developing and applying new models and methods to emerging data available about online social networks, as well as "digital traces" regarding face-to-face networks. Levels of analysis In general, social networks are self-organizing, emergent, and complex, such that a globally coherent pattern appears from the local interaction of the elements that make up the system. These patterns become more apparent as network size increases. However, a global network analysis of, for example, all interpersonal relationships in the world is not feasible and is likely to contain so much information as to be uninformative. Practical limitations of computing power, ethics and participant recruitment and payment also limit the scope of a social network analysis. The nuances of a local system may be lost in a large network analysis, hence the quality of information may be more important than its scale for understanding network properties. Thus, social networks are analyzed at the scale relevant to the researcher's theoretical question. Although levels of analysis are not necessarily mutually exclusive, there are three general levels into which networks may fall: micro-level, meso-level, and macro-level. At the micro-level, social network research typically begins with an individual, snowballing as social relationships are traced, or may begin with a small group of individuals in a particular social context. Dyadic level: A dyad is a social relationship between two individuals. Network research on dyads may concentrate on structure of the relationship (e.g. multiplexity, strength), social equality, and tendencies toward reciprocity/mutuality. Triadic level: Add one individual to a dyad, and you have a triad. Research at this level may concentrate on factors such as balance and transitivity, as well as social equality and tendencies toward reciprocity/mutuality. In the balance theory of Fritz Heider the triad is the key to social dynamics. The discord in a rivalrous love triangle is an example of an unbalanced triad, likely to change to a balanced triad by a change in one of the relations. The dynamics of social friendships in society has been modeled by balancing triads. The study is carried forward with the theory of signed graphs. Actor level: The smallest unit of analysis in a social network is an individual in their social setting, i.e., an "actor" or "ego." Egonetwork analysis focuses on network characteristics, such as size, relationship strength, density, centrality, prestige and roles such as isolates, liaisons, and bridges. Such analyses, are most commonly used in the fields of psychology or social psychology, ethnographic kinship analysis or other genealogical studies of relationships between individuals. Subset level: Subset levels of network research problems begin at the micro-level, but may cross over into the meso-level of analysis. Subset level research may focus on distance and reachability, cliques, cohesive subgroups, or other group actions or behavior. In general, meso-level theories begin with a population size that falls between the micro- and macro-levels. However, meso-level may also refer to analyses that are specifically designed to reveal connections between micro- and macro-levels. Meso-level networks are low density and may exhibit causal processes distinct from interpersonal micro-level networks. Organizations: Formal organizations are social groups that distribute tasks for a collective goal. Network research on organizations may focus on either intra-organizational or inter-organizational ties in terms of formal or informal relationships. Intra-organizational networks themselves often contain multiple levels of analysis, especially in larger organizations with multiple branches, franchises or semi-autonomous departments. In these cases, research is often conducted at a work group level and organization level, focusing on the interplay between the two structures. Experiments with networked groups online have documented ways to optimize group-level coordination through diverse interventions, including the addition of autonomous agents to the groups. Randomly distributed networks: Exponential random graph models of social networks became state-of-the-art methods of social network analysis in the 1980s. This framework has the capacity to represent social-structural effects commonly observed in many human social networks, including general degree-based structural effects commonly observed in many human social networks as well as reciprocity and transitivity, and at the node-level, homophily and attribute-based activity and popularity effects, as derived from explicit hypotheses about dependencies among network ties. Parameters are given in terms of the prevalence of small subgraph configurations in the network and can be interpreted as describing the combinations of local social processes from which a given network emerges. These probability models for networks on a given set of actors allow generalization beyond the restrictive dyadic independence assumption of micro-networks, allowing models to be built from theoretical structural foundations of social behavior. Scale-free networks: A scale-free network is a network whose degree distribution follows a power law, at least asymptotically. In network theory a scale-free ideal network is a random network with a degree distribution that unravels the size distribution of social groups. Specific characteristics of scale-free networks vary with the theories and analytical tools used to create them, however, in general, scale-free networks have some common characteristics. One notable characteristic in a scale-free network is the relative commonness of vertices with a degree that greatly exceeds the average. The highest-degree nodes are often called "hubs", and may serve specific purposes in their networks, although this depends greatly on the social context. Another general characteristic of scale-free networks is the clustering coefficient distribution, which decreases as the node degree increases. This distribution also follows a power law. The Barabási model of network evolution shown above is an example of a scale-free network. Rather than tracing interpersonal interactions, macro-level analyses generally trace the outcomes of interactions, such as economic or other resource transfer interactions over a large population. Large-scale networks: Large-scale network is a term somewhat synonymous with "macro-level." It is primarily used in social and behavioral sciences, and in economics. Originally, the term was used extensively in the computer sciences (see large-scale network mapping). Complex networks: Most larger social networks display features of social complexity, which involves substantial non-trivial features of network topology, with patterns of complex connections between elements that are neither purely regular nor purely random (see, complexity science, dynamical system and chaos theory), as do biological, and technological networks. Such complex network features include a heavy tail in the degree distribution, a high clustering coefficient, assortativity or disassortativity among vertices, community structure (see stochastic block model), and hierarchical structure. In the case of agency-directed networks these features also include reciprocity, triad significance profile (TSP, see network motif), and other features. In contrast, many of the mathematical models of networks that have been studied in the past, such as lattices and random graphs, do not show these features. Theoretical links Various theoretical frameworks have been imported for the use of social network analysis. The most prominent of these are Graph theory, Balance theory, Social comparison theory, and more recently, the Social identity approach. Few complete theories have been produced from social network analysis. Two that have are structural role theory and heterophily theory. The basis of Heterophily Theory was the finding in one study that more numerous weak ties can be important in seeking information and innovation, as cliques have a tendency to have more homogeneous opinions as well as share many common traits. This homophilic tendency was the reason for the members of the cliques to be attracted together in the first place. However, being similar, each member of the clique would also know more or less what the other members knew. To find new information or insights, members of the clique will have to look beyond the clique to its other friends and acquaintances. This is what Granovetter called "the strength of weak ties". Structural holes In the context of networks, social capital exists where people have an advantage because of their location in a network. Contacts in a network provide information, opportunities and perspectives that can be beneficial to the central player in the network. Most social structures tend to be characterized by dense clusters of strong connections. Information within these clusters tends to be rather homogeneous and redundant. Non-redundant information is most often obtained through contacts in different clusters. When two separate clusters possess non-redundant information, there is said to be a structural hole between them. Thus, a network that bridges structural holes will provide network benefits that are in some degree additive, rather than overlapping. An ideal network structure has a vine and cluster structure, providing access to many different clusters and structural holes. Networks rich in structural holes are a form of social capital in that they offer information benefits. The main player in a network that bridges structural holes is able to access information from diverse sources and clusters. For example, in business networks, this is beneficial to an individual's career because he is more likely to hear of job openings and opportunities if his network spans a wide range of contacts in different industries/sectors. This concept is similar to Mark Granovetter's theory of weak ties, which rests on the basis that having a broad range of contacts is most effective for job attainment. Structural holes have been widely applied in social network analysis, resulting in applications in a wide range of practical scenarios as well as machine learning-based social prediction. Research clusters Research has used network analysis to examine networks created when artists are exhibited together in museum exhibition. Such networks have been shown to affect an artist's recognition in history and historical narratives, even when controlling for individual accomplishments of the artist. Other work examines how network grouping of artists can affect an individual artist's auction performance. An artist's status has been shown to increase when associated with higher status networks, though this association has diminishing returns over an artist's career. In J.A. Barnes' day, a "community" referred to a specific geographic location and studies of community ties had to do with who talked, associated, traded, and attended church with whom. Today, however, there are extended "online" communities developed through telecommunications devices and social network services. Such devices and services require extensive and ongoing maintenance and analysis, often using network science methods. Community development studies, today, also make extensive use of such methods. Complex networks require methods specific to modelling and interpreting social complexity and complex adaptive systems, including techniques of dynamic network analysis. Mechanisms such as Dual-phase evolution explain how temporal changes in connectivity contribute to the formation of structure in social networks. The study of social networks is being used to examine the nature of interdependencies between actors and the ways in which these are related to outcomes of conflict and cooperation. Areas of study include cooperative behavior among participants in collective actions such as protests; promotion of peaceful behavior, social norms, and public goods within communities through networks of informal governance; the role of social networks in both intrastate conflict and interstate conflict; and social networking among politicians, constituents, and bureaucrats. In criminology and urban sociology, much attention has been paid to the social networks among criminal actors. For example, murders can be seen as a series of exchanges between gangs. Murders can be seen to diffuse outwards from a single source, because weaker gangs cannot afford to kill members of stronger gangs in retaliation, but must commit other violent acts to maintain their reputation for strength. Diffusion of ideas and innovations studies focus on the spread and use of ideas from one actor to another or one culture and another. This line of research seeks to explain why some become "early adopters" of ideas and innovations, and links social network structure with facilitating or impeding the spread of an innovation. A case in point is the social diffusion of linguistic innovation such as neologisms. Experiments and large-scale field trials (e.g., by Nicholas Christakis and collaborators) have shown that cascades of desirable behaviors can be induced in social groups, in settings as diverse as Honduras villages, Indian slums, or in the lab. Still other experiments have documented the experimental induction of social contagion of voting behavior, emotions, risk perception, and commercial products. In demography, the study of social networks has led to new sampling methods for estimating and reaching populations that are hard to enumerate (for example, homeless people or intravenous drug users.) For example, respondent driven sampling is a network-based sampling technique that relies on respondents to a survey recommending further respondents. The field of sociology focuses almost entirely on networks of outcomes of social interactions. More narrowly, economic sociology considers behavioral interactions of individuals and groups through social capital and social "markets". Sociologists, such as Mark Granovetter, have developed core principles about the interactions of social structure, information, ability to punish or reward, and trust that frequently recur in their analyses of political, economic and other institutions. Granovetter examines how social structures and social networks can affect economic outcomes like hiring, price, productivity and innovation and describes sociologists' contributions to analyzing the impact of social structure and networks on the economy. Analysis of social networks is increasingly incorporated into health care analytics, not only in epidemiological studies but also in models of patient communication and education, disease prevention, mental health diagnosis and treatment, and in the study of health care organizations and systems. Human ecology is an interdisciplinary and transdisciplinary study of the relationship between humans and their natural, social, and built environments. The scientific philosophy of human ecology has a diffuse history with connections to geography, sociology, psychology, anthropology, zoology, and natural ecology. In the study of literary systems, network analysis has been applied by Anheier, Gerhards and Romo, De Nooy, Senekal, and Lotker, to study various aspects of how literature functions. The basic premise is that polysystem theory, which has been around since the writings of Even-Zohar, can be integrated with network theory and the relationships between different actors in the literary network, e.g. writers, critics, publishers, literary histories, etc., can be mapped using visualization from SNA. Research studies of formal or informal organization relationships, organizational communication, economics, economic sociology, and other resource transfers. Social networks have also been used to examine how organizations interact with each other, characterizing the many informal connections that link executives together, as well as associations and connections between individual employees at different organizations. Many organizational social network studies focus on teams. Within team network studies, research assesses, for example, the predictors and outcomes of centrality and power, density and centralization of team instrumental and expressive ties, and the role of between-team networks. Intra-organizational networks have been found to affect organizational commitment, organizational identification, interpersonal citizenship behaviour. Social capital is a form of economic and cultural capital in which social networks are central, transactions are marked by reciprocity, trust, and cooperation, and market agents produce goods and services not mainly for themselves, but for a common good. Social capital is split into three dimensions: the structural, the relational and the cognitive dimension. The structural dimension describes how partners interact with each other and which specific partners meet in a social network. Also, the structural dimension of social capital indicates the level of ties among organizations. This dimension is highly connected to the relational dimension which refers to trustworthiness, norms, expectations and identifications of the bonds between partners. The relational dimension explains the nature of these ties which is mainly illustrated by the level of trust accorded to the network of organizations. The cognitive dimension analyses the extent to which organizations share common goals and objectives as a result of their ties and interactions. Social capital is a sociological concept about the value of social relations and the role of cooperation and confidence to achieve positive outcomes. The term refers to the value one can get from their social ties. For example, newly arrived immigrants can make use of their social ties to established migrants to acquire jobs they may otherwise have trouble getting (e.g., because of unfamiliarity with the local language). A positive relationship exists between social capital and the intensity of social network use. In a dynamic framework, higher activity in a network feeds into higher social capital which itself encourages more activity. This particular cluster focuses on brand-image and promotional strategy effectiveness, taking into account the impact of customer participation on sales and brand-image. This is gauged through techniques such as sentiment analysis which rely on mathematical areas of study such as data mining and analytics. This area of research produces vast numbers of commercial applications as the main goal of any study is to understand consumer behaviour and drive sales. In many organizations, members tend to focus their activities inside their own groups, which stifles creativity and restricts opportunities. A player whose network bridges structural holes has an advantage in detecting and developing rewarding opportunities. Such a player can mobilize social capital by acting as a "broker" of information between two clusters that otherwise would not have been in contact, thus providing access to new ideas, opinions and opportunities. British philosopher and political economist John Stuart Mill, writes, "it is hardly possible to overrate the value of placing human beings in contact with persons dissimilar to themselves.... Such communication [is] one of the primary sources of progress." Thus, a player with a network rich in structural holes can add value to an organization through new ideas and opportunities. This in turn, helps an individual's career development and advancement. A social capital broker also reaps control benefits of being the facilitator of information flow between contacts. Full communication with exploratory mindsets and information exchange generated by dynamically alternating positions in a social network promotes creative and deep thinking. In the case of consulting firm Eden McCallum, the founders were able to advance their careers by bridging their connections with former big three consulting firm consultants and mid-size industry firms. By bridging structural holes and mobilizing social capital, players can advance their careers by executing new opportunities between contacts. There has been research that both substantiates and refutes the benefits of information brokerage. A study of high tech Chinese firms by Zhixing Xiao found that the control benefits of structural holes are "dissonant to the dominant firm-wide spirit of cooperation and the information benefits cannot materialize due to the communal sharing values" of such organizations. However, this study only analyzed Chinese firms, which tend to have strong communal sharing values. Information and control benefits of structural holes are still valuable in firms that are not quite as inclusive and cooperative on the firm-wide level. In 2004, Ronald Burt studied 673 managers who ran the supply chain for one of America's largest electronics companies. He found that managers who often discussed issues with other groups were better paid, received more positive job evaluations and were more likely to be promoted. Thus, bridging structural holes can be beneficial to an organization, and in turn, to an individual's career. Computer networks combined with social networking software produce a new medium for social interaction. A relationship over a computerized social networking service can be characterized by context, direction, and strength. The content of a relation refers to the resource that is exchanged. In a computer-mediated communication context, social pairs exchange different kinds of information, including sending a data file or a computer program as well as providing emotional support or arranging a meeting. With the rise of electronic commerce, information exchanged may also correspond to exchanges of money, goods or services in the "real" world. Social network analysis methods have become essential to examining these types of computer mediated communication. In addition, the sheer size and the volatile nature of social media has given rise to new network metrics. A key concern with networks extracted from social media is the lack of robustness of network metrics given missing data. Based on the pattern of homophily, ties between people are most likely to occur between nodes that are most similar to each other, or within neighbourhood segregation, individuals are most likely to inhabit the same regional areas as other individuals who are like them. Therefore, social networks can be used as a tool to measure the degree of segregation or homophily within a social network. Social Networks can both be used to simulate the process of homophily but it can also serve as a measure of level of exposure of different groups to each other within a current social network of individuals in a certain area. See also References Further reading External links |
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