United States

The United States of America ( USA ) , commonly known as the United States ( U.S. ) or America , is a constitutional federal republic composed of 50 states , a federal district , five major self-governing territories , and various possessions .  Forty-eight of the fifty states and the federal district are contiguous and located in North America between Canada and Mexico . The state of Alaska is in the northwest corner of North America , bordered by Canada to the east and across the Bering Strait from Russia to the west . The state of Hawaii is an archipelago in the mid-Pacific Ocean . The U.S. territories are scattered about the Pacific Ocean and the Caribbean Sea . Nine time zones are covered . The geography , climate and wildlife of the country are extremely diverse .   At 3.8 million square miles ( 9.8 million km2 ) and with over 324 million people , the United States is the world 's third - or fourth-largest country by total area , third-largest by land area , and the third-most populous . It is one of the world 's most ethnically diverse and multicultural nations , and is home to the world 's largest immigrant population . The capital is Washington , D.C. , and the largest city is New York City ; nine other major metropolitan areas -- each with at least 4.5 million inhabitants and the largest having more than 13 million people -- are Los Angeles , Chicago , Dallas , Houston , Philadelphia , Miami , Atlanta , Boston , and San Francisco .   Paleo-Indians migrated from Asia to the North American mainland at least 15,000 years ago . European colonization began in the 16th century . The United States emerged from 13 British colonies along the East Coast . Numerous disputes between Great Britain and the colonies following the Seven Years ' War led to the American Revolution , which began in 1775 . On July 4 , 1776 , during the course of the American Revolutionary War , the colonies unanimously adopted the Declaration of Independence . The war ended in 1783 with recognition of the independence of the United States by Great Britain , representing the first successful war of independence against a European power . The current constitution was adopted in 1788 , after the Articles of Confederation , adopted in 1781 , were felt to have provided inadequate federal powers . The first ten amendments , collectively named the Bill of Rights , were ratified in 1791 and designed to guarantee many fundamental civil liberties .   The United States embarked on a vigorous expansion across North America throughout the 19th century , displacing Native American tribes , acquiring new territories , and gradually admitting new states until it spanned the continent by 1848 . During the second half of the 19th century , the American Civil War led to the end of legal slavery in the country . By the end of that century , the United States extended into the Pacific Ocean , and its economy , driven in large part by the Industrial Revolution , began to soar . The Spanish -- American War and confirmed the country 's status as a global military power . The United States emerged from as a global superpower , the first country to develop nuclear weapons , the only country to use them in warfare , and a permanent member of the United Nations Security Council . The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the world 's sole superpower . The U.S. is a founding member of the United Nations , World Bank , International Monetary Fund , Organization of American States ( OAS ) , and other international organizations .   The United States is a highly developed country , with the world 's largest economy by nominal GDP and second-largest economy by PPP . Though its population is only 4.3 % of the world total , Americans hold nearly 40 % of the total wealth in the world . The United States ranks among the highest in several measures of socioeconomic performance , including average wage , human development , per capita GDP , and productivity per person . While the U.S. economy is considered post-industrial , characterized by the dominance of services and knowledge economy , the manufacturing sector remains the second-largest in the world . Accounting for approximately a quarter of global GDP and a third of global military spending , the United States is the world 's foremost economic and military power . The United States is a prominent political and cultural force internationally , and a leader in scientific research and technological innovations .


The United States Department of Homeland Security ( DHS ) is a cabinet department of the United States federal government with responsibilities in public security , roughly comparable to the interior or home ministries of other countries . Its stated missions involve anti-terrorism , border security , immigration and customs , cyber security , and disaster prevention and management . It was created in response to the September 11 attacks .   In fiscal year 2017 , it was allocated a net discretionary budget of $ 40.6 billion . With more than 240,000 employees , DHS is the third largest Cabinet department , after the Departments of Defense and Veterans Affairs . Homeland security policy is coordinated at the White House by the Homeland Security Council . Other agencies with significant homeland security responsibilities include the Departments of Health and Human Services , Justice , and Energy .   __ TOC __


The United States Environmental Protection Agency ( EPA or sometimes USEPA ) is an agency of the Federal government of the United States which was created for the purpose of protecting human health and the environment by writing and enforcing regulations based on laws passed by Congress . President Richard Nixon proposed the establishment of EPA and it began operation on December 2 , 1970 , after Nixon signed an executive order . The order establishing the EPA was ratified by committee hearings in the House and Senate . The agency is led by its Administrator , who is appointed by the President and approved by Congress . The current Administrator is Scott Pruitt . The EPA is not a Cabinet department , but the Administrator is normally given cabinet rank .   The EPA has its headquarters in Washington , D.C. , regional offices for each of the agency 's ten regions , and 27 laboratories . The agency conducts environmental assessment , research , and education . It has the responsibility of maintaining and enforcing national standards under a variety of environmental laws , in consultation with state , tribal , and local governments . It delegates some permitting , monitoring , and enforcement responsibility to U.S. states and the federally recognized tribes . EPA enforcement powers include fines , sanctions , and other measures . The agency also works with industries and all levels of government in a wide variety of voluntary pollution prevention programs and energy conservation efforts .   In 2016 , the agency had 15,376 full-time employees . More than half of EPA 's employees are engineers , scientists , and environmental protection specialists ; other employees include legal , public affairs , financial , and information technologists . In 2017 the Trump administration proposed a 31 % cut to the EPA 's budget to $ 5.7 billion from $ 8.1 billion and to eliminate a quarter of the agency jobs .


United States Forest Service

The United States Forest Service ( USFS ) is an agency of the U.S. Department of Agriculture that administers the nation 's 154 national forests and 20 national grasslands , which encompass 193 e6acre . Major divisions of the agency include the National Forest System , State and Private Forestry , Business Operations , and the Research and Development branch . Managing approximately 25 % of federal lands , it is the only major national land agency that is outside the U.S. Department of the Interior .


United States federal budget

The United States federal budget comprises the spending and revenues of the US federal government . The budget is the financial representation of the priorities of the government , reflecting historical debates and competing economic philosophies . The government primarily spends on healthcare , retirement , and defense programs . The non-partisan Congressional Budget Office provides extensive analysis of the budget and its economic effects . It has reported that the U.S. is facing a series of long-term financial challenges , as the country ages and healthcare costs continue growing faster than the economy .


United States labor law

United States labor law sets the rights and duties for employees , labor unions , and employers in the United States . Labor law 's basic aim is to remedy the `` inequality of bargaining power '' between employees and employers , especially employers `` organized in the corporate or other forms of ownership association '' . Over the 20th century , federal law created a series of minimum social and economic rights , and encouraged state laws to go beyond the minimum to favor employees . The Fair Labor Standards Act of 1938 requires a federal minimum wage , currently $ 7.25 but higher in 28 states , and discourages unhealthy working weeks over 40 hours through time-and-a-half overtime pay . Unlike every other democratic country , there are no federal or state laws requiring paid holidays or paid family leave : the Family and Medical Leave Act of 1993 creates a limited right to 12 weeks of unpaid leave in larger employers . There is no automatic right to an occupational pension beyond federally guaranteed social security , but the Employee Retirement Income Security Act of 1974 requires standards of prudent management and good governance if employers agree to provide pensions , health plans or other benefits . The Occupational Safety and Health Act of 1970 requires employees have a safe system of work . A contract of employment can always improve standards beyond the minimum statutory rights . To get fair terms beyond the statutory minimum , and improve upon individual contracts , employees must organize a labor union for collective bargaining . The National Labor Relations Act of 1935 creates rights for most employees to organize a labor union , without any detriment through unfair labor practices . Under the Labor Management Reporting and Disclosure Act of 1959 , labor union governance follows democratic principles . In any workplace where a majority of employees support a union , employing entities have a duty to bargain in good faith . Unions can take collective action to defend their interests , including withdrawing their labor on strike . There are not yet general rights to directly participate in enterprise governance , but many employees and unions have experimented with securing representation on corporate boards .   Since the Civil Rights Act of 1964 , all employing entities and labor unions have a duty to treat employees equally , without discrimination based on `` race , color , religion , sex , or national origin . '' There are separate rules for sex discrimination in pay under the Equal Pay Act of 1963 . Additional groups with `` protected status '' were added by the Age Discrimination in Employment Act of 1967 and the Americans with Disabilities Act of 1990 . There is no federal law banning all sexual orientation or identity discrimination , but 22 states had passed laws by 2016 . These equality laws generally prevent discrimination in hiring , terms of employment , and make discharge because of a protected characteristic unlawful . There is not a federal law against unjust discharge , and most states also have no law with full protection against wrongful termination of employment . Job security rights in the US are not weaker than in all other industrialized countries . On the other hand , collective agreements made by labor unions and many individual contracts often require people are only discharged for a `` just cause '' . The Worker Adjustment and Retraining Notification Act of 1988 requires employing entities give 60 days notice if more than 50 or one third of the workforce may lose their jobs . Federal law has sought to reach full employment through monetary policy and spending on infrastructure . Trade policy has increasingly attempted to put labor rights in international agreements , to ensure that open markets in a global economy do not lead to more unemployment in the United States of America .


United States withdrawal from the Paris Agreement

On June 1, 2017, United States President Donald Trump announced that the U.S. would cease all participation in the 2015 Paris Agreement on climate change mitigation, and begin negotiations to re-enter the agreement "on terms that are fair to the United States, its businesses, its workers, its people, its taxpayers," or form a new agreement. In withdrawing from the agreement, Trump stated that "The Paris accord will undermine (the U.S.) economy," and "puts (the U.S.) at a permanent disadvantage." Trump stated that the withdrawal would be in accordance with his America First policy. In accordance with Article 28 of the Paris Agreement, a country cannot give notice of withdrawal from the agreement before three years of its start date in the relevant country, which was on November 4, 2016 in the case of the United States. The White House later clarified that the U.S. will abide by the four-year exit process. On November 4, 2019, the administration gave a formal notice of intention to withdraw, which takes 12 months to take effect.  Until the withdrawal took effect, the United States was obligated to maintain its commitments under the Agreement, such as the requirement to continue reporting its emissions to the United Nations. The withdrawal took effect on November 4, 2020, one day after the 2020 U.S. presidential election.While celebrated by some members of the Republican Party, international reactions to the withdrawal were overwhelmingly negative from across the political spectrum, and the decision received substantial criticism from religious organizations, businesses, political leaders of all parties, environmentalists, and scientists and citizens from the United States and internationally.Following Trump's announcement, the governors of several U.S. states formed the United States Climate Alliance to continue to advance the objectives of the Paris Agreement at the state level despite the federal withdrawal. As of July 1, 2019, 24 states, American Samoa, and Puerto Rico have joined the alliance, and similar commitments have also been expressed by other state governors, mayors, and businesses.Trump's withdrawal from the Paris agreement will impact other countries by reducing its financial aid to the Green Climate fund. The termination of the $3 billion U.S. funding will ultimately impact climate change research and decrease society's chance of reaching the Paris Agreement goals, as well as omit U.S. contributions to the future IPCC reports. Trump's decision will also affect the carbon emission space as well as the carbon price. The U.S.'s withdrawal will also mean that the spot to take over the global climate regime will be obtainable for China and the EU.President-elect Joe Biden vowed to rejoin the Paris Agreement on his first day in office.


University of Massachusetts Amherst

The University of Massachusetts Amherst ( abbreviated UMass Amherst and colloquially referred to as UMass or Massachusetts ) is a public research and land-grant university in Amherst , Massachusetts , United States , and the flagship of the University of Massachusetts system . With approximately 1,300 faculty members and more than 29,000 students , UMass Amherst is the largest public university in New England and is ranked as tied for the 27th best public university in the nation .   The university offers bachelor 's degrees , master 's degrees , and doctoral degrees in 111 undergraduate , 75 master 's and 47 doctoral programs in nine schools and colleges . The main campus is situated north of downtown Amherst . In a 2009 article for MSN.com , Amherst was ranked first in Best College Towns in the United States . In 2012 , U.S. News and World Report ranked Amherst among the Top 10 Great College Towns in America . It is also a member of the Five College Consortium .   The University of Massachusetts Amherst is categorized as a Research University with Highest research activity by the Carnegie Foundation for the Advancement of Teaching . In fiscal year 2014 , UMass Amherst had research expenditures exceeding $ 200 million .   UMass Amherst sports teams are called the Minutemen and Minutewomen , the colors being maroon , black , and white ; the school mascot is Sam the Minuteman . All teams participate in NCAA Division I . The university is a member of the Atlantic 10 Conference , while playing ice hockey in Hockey East and football as an FBS Independent .


University of Oxford

The University of Oxford ( informally Oxford University or simply Oxford ) is a collegiate research university located in Oxford , England . It has no known date of foundation , but there is evidence of teaching as far back as 1096 , making it the oldest university in the English-speaking world and the world 's second-oldest university in continuous operation . It is one of the world 's most prestigious universities . It grew rapidly from 1167 when Henry II banned English students from attending the University of Paris . After disputes between students and Oxford townsfolk in 1209 , some academics fled north-east to Cambridge where they established what became the University of Cambridge . The two `` ancient universities '' are frequently jointly referred to as `` Oxbridge '' .   The university is made up of a variety of institutions , including 38 constituent colleges and a full range of academic departments which are organised into four divisions . All the colleges are self-governing institutions within the university , each controlling its own membership and with its own internal structure and activities . Being a city university , it does not have a main campus ; instead , its buildings and facilities are scattered throughout the city centre . Most undergraduate teaching at Oxford is organised around weekly tutorials at the colleges and halls , supported by classes , lectures and laboratory work provided by university faculties and departments .   Oxford is the home of the Rhodes Scholarship , one of the world 's oldest and most prestigious scholarships , which has brought graduate students to study at the university for more than a century . The university operates the world 's oldest university museum , as well as the largest university press in the world and the largest academic library system in Britain . Oxford has educated many notable alumni , including 28 Nobel laureates , 27 Prime Ministers of the United Kingdom , and many heads of state and government around the world .


Upper Atmosphere Research Satellite

The Upper Atmosphere Research Satellite ( UARS ) was a NASA-operated orbital observatory whose mission was to study the Earth 's atmosphere , particularly the protective ozone layer . The 5900 kg satellite was deployed from Space Shuttle Discovery during the STS-48 mission on 15 September 1991 . It entered Earth orbit at an operational altitude of 600 km , with an orbital inclination of 57 degrees .   The original mission duration was to be only three years , but was extended several times . When the mission finally ended in June 2005 due to funding cuts , 14 years after the satellite 's launch , six of its ten instruments were still operational . A final orbit-lowering burn was performed in early December 2005 to prepare the satellite for deorbit . On 26 October 2010 , the International Space Station performed a debris-avoidance maneuver in response to a conjunction with UARS .   The decommissioned satellite re-entered Earth 's atmosphere on 24 September 2011 . Considerable media attention surrounded the event , largely due to NASA 's predictions that substantial parts of the satellite might reach the ground , potentially endangering inhabited areas . However , the satellite ultimately impacted in a remote area of the Pacific Ocean .


Uppsala

Uppsala ( -LSB- ² ɵpːsɑːla -RSB- ; older spelling Upsala ) is the capital of Uppsala County and the fourth largest city of Sweden , after Stockholm , Gothenburg and Malmö . It had 149,245 inhabitants in 2015 .   Located 71 km north of the capital Stockholm , it is also the seat of Uppsala Municipality . Since 1164 , Uppsala has been the ecclesiastical centre of Sweden , being the seat of the Archbishop of the Church of Sweden . Uppsala is home to Scandinavia 's largest cathedral -- Uppsala Cathedral . Founded in 1477 , Uppsala University is the oldest centre of higher education in Scandinavia . Among many achievements , the Celsius scale for temperature was invented there .


Uptick rule

The uptick rule is a trading restriction that states that short selling a stock is only allowed on an uptick . For the rule to be satisfied , the short must be either at a price above the last traded price of the security , or at the last traded price when the most recent movement between traded prices was upward ( i.e. the security has traded below the last-traded price more recently than above that price ) .   The U.S. Securities and Exchange Commission ( SEC ) defined the rule , and summarized it :  `` Rule 10a-1 ( a ) ( 1 ) provided that , subject to certain exceptions , a listed security may be sold short ( A ) at a price above the price at which the immediately preceding sale was effected ( plus tick ) , or ( B ) at the last sale price if it is higher than the last different price ( zero-plus tick ) . Short sales were not permitted on minus ticks or zero-minus ticks , subject to narrow exceptions . ''   The rule went into effect in 1938 and was removed when Rule 201 Regulation SHO became effective in 2007 . In 2009 , the reintroduction of the uptick rule was widely debated , and proposals for a form of its reintroduction by the SEC went into a public comment period on 2009-04-08 . A modified form of the rule was adopted on 2010-02-24 .


Uranus

Uranus is the seventh planet from the Sun . It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System . Uranus is similar in composition to Neptune , and both have different bulk chemical composition from that of the larger gas giants Jupiter and Saturn . For this reason , scientists often classify Uranus and Neptune as `` ice giants '' to distinguish them from the gas giants . Uranus 's atmosphere is similar to Jupiter 's and Saturn 's in its primary composition of hydrogen and helium , but it contains more `` ices '' such as water , ammonia , and methane , along with traces of other hydrocarbons . It is the coldest planetary atmosphere in the Solar System , with a minimum temperature of 49 K , and has a complex , layered cloud structure with water thought to make up the lowest clouds and methane the uppermost layer of clouds . The interior of Uranus is mainly composed of ices and rock .   Uranus is the only planet whose name is derived from a figure from Greek mythology , from the Latinised version of the Greek god of the sky Ouranos . Like the other giant planets , Uranus has a ring system , a magnetosphere , and numerous moons . The Uranian system has a unique configuration among those of the planets because its axis of rotation is tilted sideways , nearly into the plane of its solar orbit . Its north and south poles , therefore , lie where most other planets have their equators . In 1986 , images from Voyager 2 showed Uranus as an almost featureless planet in visible light , without the cloud bands or storms associated with the other giant planets . Observations from Earth have shown seasonal change and increased weather activity as Uranus approached its equinox in 2007 . Wind speeds can reach 250 m/s .


Urban heat island

An urban heat island ( UHI ) is an urban area or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities . The temperature difference usually is larger at night than during the day , and is most apparent when winds are weak . UHI is most noticeable during the summer and winter . The main cause of the urban heat island effect is from the modification of land surfaces . Waste heat generated by energy usage is a secondary contributor . As a population center grows , it tends to expand its area and increase its average temperature . The less-used term heat island refers to any area , populated or not , which is consistently hotter than the surrounding area .   Monthly rainfall is greater downwind of cities , partially due to the UHI . Increases in heat within urban centers increases the length of growing seasons , and decreases the occurrence of weak tornadoes . The UHI decreases air quality by increasing the production of pollutants such as ozone , and decreases water quality as warmer waters flow into area streams and put stress on their ecosystems .   Not all cities have a distinct urban heat island . Mitigation of the urban heat island effect can be accomplished through the use of green roofs and the use of lighter-colored surfaces in urban areas , which reflect more sunlight and absorb less heat .   There are concerns raised about possible contribution from urban heat islands to global warming . Research on China and India indicates that urban heat island effect contributes to climate warming by about 30 % . On the other hand , one 1999 comparison between urban and rural areas proposed that the urban heat island effects have little influence on global mean temperature trends . Many studies reveal increases in the severity of the effect with the progress of climate change .


Urbanization

Urbanization refers to the population shift from rural to urban areas , `` the gradual increase in the proportion of people living in urban areas '' , and the ways in which each society adapts to the change . It is predominantly the process by which towns and cities are formed and become larger as more people begin living and working in central areas . The United Nations projected that half of the world 's population would live in urban areas at the end of 2008 . It is predicted that by 2050 about 64 % of the developing world and 86 % of the developed world will be urbanized . That is equivalent to approximately 3 billion urbanites by 2050 , much of which will occur in Africa and Asia . Notably , the United Nations has also recently projected that nearly all global population growth from 2017 to 2030 will be absorbed by cities , about 1.1 billion new urbanites over the next 13 years .   Urbanization is relevant to a range of disciplines , including geography , sociology , economics , urban planning and public health . The phenomenon has been closely linked to modernization , industrialization and the sociological process of rationalization . Urbanization can be seen as a specific condition at a set time ( e.g. the proportion of total population or area in cities or towns ) or as an increase in that condition over time . So urbanization can be quantified either in terms of , say , the level of urban development relative to the overall population , or as the rate at which the urban proportion of the population is increasing . Urbanization creates enormous social , economic and environmental changes , which provide an opportunity for sustainability with the `` potential to use resources more efficiently , to create more sustainable land use and to protect the biodiversity of natural ecosystems . ''   Urbanization is not merely a modern phenomenon , but a rapid and historic transformation of human social roots on a global scale , whereby predominantly rural culture is being rapidly replaced by predominantly urban culture . The first major change in settlement patterns was the accumulation of hunter-gatherers into villages many thousand years ago . Village culture is characterized by common bloodlines , intimate relationships and communal behavior whereas urban culture is characterized by distant bloodlines , unfamiliar relations and competitive behavior . This unprecedented movement of people is forecast to continue and intensify during the next few decades , mushrooming cities to sizes unthinkable only a century ago .   Today , in Asia the urban agglomerations of Osaka , Karachi , Jakarta , Mumbai , Shanghai , Manila , Seoul and Beijing are each already home to over 20 million people , while Delhi and Tokyo are forecast to approach or exceed 40 million people each within the coming decade . Outside Asia , Mexico City , São Paulo , London , New York City , Istanbul , Lagos and Cairo are , or soon will be , home to over 10 million people .


Uruguay

Uruguay ( -LSB- ˈjʊərəɡwaɪ -RSB- -LSB- uɾuˈɣwai̯ -RSB- ) , officially the Oriental Republic of Uruguay ( República Oriental del Uruguay ) , is a sovereign State in the southeastern region of South America . It borders Argentina to its west and Brazil to its north and east , with the Río de la Plata ( River of Silver ) to the south and the Atlantic Ocean to the southeast . Uruguay is home to an estimated 3.42 million people , of whom 1.8 million live in the metropolitan area of its capital and largest city , Montevideo . With an area of approximately 176000 km2 , Uruguay is geographically the second-smallest nation in South America , only larger in size than Suriname .   Uruguay was inhabited by the Charrúa people for approximately 4000 years before the Portuguese established Colonia del Sacramento , one of the oldest European settlements in the region , in 1680 . Montevideo was founded as a military stronghold by the Spanish in the early 18th century , signifying the competing claims over the region . Uruguay won its independence between 1811 and 1828 , following a four-way struggle between Spain , Portugal , Argentina and Brazil . It remained subject to foreign influence and intervention throughout the 19th century , with the military playing a recurring role in domestic politics until the late 20th century . Modern Uruguay is a democratic constitutional republic , with a president who serves as both head of state and head of government .   Uruguay is ranked first in Latin America in democracy , peace , lack of corruption , e-government , and is first in South America when it comes to press freedom , size of the middle class and prosperity . On a per-capita basis , Uruguay contributes more troops to United Nations peace-keeping missions than any other country . It ranks second in the region on economic freedom , income equality , per-capita income and inflows of FDI . Uruguay is the third-best country on the continent in terms of HDI , GDP growth , innovation and infrastructure . It is regarded as a high-income country ( top group ) by the UN . Uruguay is also the third-best ranked in the world in e-Participation .  Uruguay is an important global exporter of combed wool , rice , soybeans , frozen beef , malt and milk . Nearly 95 % of Uruguay 's electricity comes from renewable energy , mostly hydroelectric facilities and wind parks .   The Economist named Uruguay `` country of the year '' in 2013 , acknowledging the innovative policy of legalizing the production , sale and consumption of cannabis . Same-sex marriage and abortion are also legal , leading Uruguay to be regarded as one of the most progressive nations in the world , and one of the most socially developed , outstanding regionally , and ranking highly on global measures of personal rights , tolerance , and inclusion issues .


Usage share of operating systems

The usage share of operating systems is the percentage of the operating systems used in computing devices ( approximately market share , also discussed in the article ) .   There are `` three big personal computing platforms '' , two of which claim over 1.4 billion users , Android and Windows . The third `` platform '' or strictly two ( or three ) platformsApple 's iOS and macOS combined , have over 1 billion users . Historically Windows running on desktop computers was dominant ( Macintosh computers were previously the more popular desktop computers , and those followed the mainframe computer-era ) , for a 25 year period from the early 1990s to 2016 . From late 2016 the mobile era took over , with the desktop computers ' market share ( measured by web usage ; including macOS ) was down to 45.22 % in January 2017 , an `` end of an era '' was declared by StatCounter for Windows ( and the desktop in general ) as no longer most popular , since smartphones alone , ( excluding tablets ) , because of Android , have majority use globally .   Different categories of computers use a wide variety of operating systems ( OS ) . Windows gained majority usage share in the 1990s , on desktops ( the computer platform then taking over ) , eventually described as `` dominant '' ( and still has a majority as a `` desktop OS '' ) but is not dominant across all platforms ( while latest version runs on all platforms ) . On smartphones , Android is dominant by any metric ; its installed base is 1.8 billion , which tops Windows on PCs . No operating system has a clear majority across all platforms or all regions ; as judged by web usea proxy for all useAndroid has surpassed Windows , when counted across all platforms and regions . Android is the highest ranked OS in most countries of the world ( even a few in Europe , such as Poland with majority use ) ; leading to it ( with some help from other mobile operating systems such as Apple 's ) eventually , in late 2016 , making the world smartphone-majority . Android alone explains that to a large degree , smartphones alone have majority use , where Android is dominant . Android has over half the usage share across platforms ( even with it not used much on desktops ) in the two biggest continents ( and most populous with 76 % combined ) , Africa and Asia . For brief periods , countries on other continents , such as the United States , have lost desktops-majority share ; that has also happened for South America .   Since 2013 , devices running Android have been selling more than Windows , iOS and macOS devices combined . That made Android the most popular operating system that runs on smartphones , while iOS is more used on tablets . Most desktop and laptop computers use Microsoft Windows , while virtually all supercomputers ( and for over a decade back ) use Linux . In the servers category , there is more diversity , with Linux and Windows Server most popular , and many fewer mainframes . Data about operating system share is difficult to obtain , since in most categories there are few reliable primary sources or agreed methodologies for its collection .


Valencia

Valencia ( -LSB- vəˈlɛnsiə -RSB- -LSB- baˈlenθja -RSB- ) , officially València ( -LSB- vaˈlensia -RSB- ) , is the capital of the autonomous community of Valencia and the third largest city in Spain after Madrid and Barcelona , with around 800,000 inhabitants in the administrative centre . Its urban area extends beyond the administrative city limits with a population of around 1.5 -- 1.6 million people . Valencia is Spain 's third largest metropolitan area , with a population ranging from 1.7 to 2.5 million . The Port of Valencia is the 5th busiest container port in Europe and the busiest container port on the Mediterranean Sea . The city is ranked at Gamma in the Globalization and World Cities Research Network .   Valencia was founded as a Roman colony by the consul Decimus Junius Brutus Callaicus in 138 BC , and called Valentia Edetanorum . In 714 Moroccan and Arab Moors occupied the city , introducing their language , religion and customs ; they implemented improved irrigation systems and the cultivation of new crops as well , being capital of the Taifa of Valencia . In 1238 the Christian king James I of Aragon reconquered the city and divided the land among the nobles who helped him conquer it , as witnessed in the Llibre del Repartiment . He also created a new law for the city , the Furs of Valencia , which were extended to the rest of the Kingdom of Valencia . In the 18th century Philip V of Spain abolished the privileges as punishment to the kingdom of Valencia for aligning with the Habsburg side in the War of the Spanish Succession . Valencia was the capital of Spain when Joseph Bonaparte moved the Court there in the summer of 1812 . It also served as capital between 1936 and 1937 , during the Second Spanish Republic .   The city is situated on the banks of the Turia , on the east coast of the Iberian Peninsula , fronting the Gulf of Valencia on the Mediterranean Sea . Its historic centre is one of the largest in Spain , with approximately 169 hectares ; this heritage of ancient monuments , views and cultural attractions makes Valencia one of the country 's most popular tourist destinations .   Valencia is integrated into an industrial area on the Costa del Azahar ( Orange Blossom Coast ) . Valencia 's main festival is the Falles . The traditional Spanish dish , paella , originated in Valencia .


Valero Energy

Valero Energy Corporation is a Fortune 500 international manufacturer and marketer of transportation fuels , other petrochemical products , and power . It is headquartered in San Antonio , Texas , United States . The company owns and operates 16 refineries throughout the United States , Canada , United Kingdom , and the Caribbean with a combined throughput capacity of approximately 3 Moilbbl per day , 11 ethanol plants with a combined production capacity of 1.2 e9USgal per year , and a 50-megawatt wind farm . Before the 2013 spinoff of CST Brands , Valero was one of the United States ' largest retail operators with approximately 6,800 retail and branded wholesale outlets in the United States , Canada , United Kingdom , and the Caribbean under the Valero , Diamond Shamrock , Shamrock , Ultramar , Beacon , and Texaco brands .


Variable renewable energy

Variable renewable energy ( VRE ) is a renewable energy source that is non-dispatchable due to its fluctuating nature , like wind power and solar power , as opposed to a controllable renewable energy source such as hydroelectricity , or biomass , or a relatively constant source such as geothermal power or run-of-the-river hydroelectricity .


Variable star

A variable star is a star whose brightness as seen from Earth ( its apparent magnitude ) fluctuates .   This variation may be caused by a change in emitted light or by something partly blocking the light , so variable stars are classified as either :  Intrinsic variables , whose luminosity actually changes ; for example , because the star periodically swells and shrinks .  Extrinsic variables , whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth ; for example , because the star has an orbiting companion that sometimes eclipses it .   Many , possibly most , stars have at least some variation in luminosity : the energy output of our Sun , for example , varies by about 0.1 % over an 11-year solar cycle .


Veganism

Veganism is both the practice of abstaining from the use of animal products , particularly in diet , and an associated philosophy that rejects the commodity status of animals . A follower of either the diet or the philosophy is known as a vegan ( pronounced ) .   Distinctions are sometimes made between several categories of veganism . Dietary vegans ( or strict vegetarians ) refrain from consuming animal products , not only meat but also eggs , dairy products and other animal-derived substances . The term ethical vegan is often applied to those who not only follow a vegan diet but extend the philosophy into other areas of their lives , and oppose the use of animals for any purpose . Another term is environmental veganism , which refers to the avoidance of animal products on the premise that the harvesting or industrial farming of animals is environmentally damaging and unsustainable .   Donald Watson coined the term vegan in 1944 when he co-founded the Vegan Society in England . At first he used it to mean `` non-dairy vegetarian '' , but from 1951 the society defined it as `` the doctrine that man should live without exploiting animals '' . Interest in veganism increased in the 2010s . More vegan stores opened , and vegan options became increasingly available in supermarkets and restaurants in many countries .   Vegan diets tend to be higher in dietary fibre , magnesium , folic acid , vitamin C , vitamin E , iron and phytochemicals , and lower in dietary energy , saturated fat , cholesterol , long-chain omega-3 fatty acids , vitamin D , calcium , zinc and vitamin B12 . Well-planned vegan diets can reduce the risk of some types of chronic disease , including heart disease . They are regarded as appropriate for all stages of the life-cycle by the American Academy of Nutrition and Dietetics . The German Society for Nutrition cautions against vegan diets for children , and during pregnancy and lactation . Because uncontaminated plant foods do not provide vitamin B12 ( which is produced by microorganisms such as bacteria ) , researchers agree that vegans should eat B12-fortified foods or take a supplement .


Vegetarianism

Vegetarianism -LSB- vɛdʒɪˈtɛəriənɪzəm -RSB- is the practice of abstaining from the consumption of meat ( red meat , poultry , seafood , and the flesh of any other animal ) , and may also include abstention from by-products of animal slaughter .   Vegetarianism may be adopted for various reasons . Many people object to eating meat out of respect for sentient life . Such ethical motivations have been codified under various religious beliefs , as well as animal rights advocacy . Other motivations for vegetarianism are health-related , political , environmental , cultural , aesthetic , economic , or personal preference . There are variations of the diet as well : an ovo-lacto vegetarian diet includes both eggs and dairy products , an ovo-vegetarian diet includes eggs but not dairy products , and a lacto-vegetarian diet includes dairy products but not eggs . A vegan diet excludes all animal products , including eggs and dairy . Some vegans also avoid other animal products such as beeswax , leather or silk clothing , and goose-fat shoe polish .   Packaged and processed foods , such as cakes , cookies , candies , chocolate , yogurt , and marshmallows , often contain unfamiliar animal ingredients , so may be a special concern for vegetarians due to the likelihood of such additions . Often , prior to purchase or consumption , vegetarians will scrutinize products for animal-derived ingredients . Vegetarians ' feelings vary with regard to these ingredients . For example , while some vegetarians may be unaware of animal-derived rennet 's role in the production of cheese , and may therefore unknowingly consume the product , other vegetarians may not take issue with its consumption .   Semi-vegetarian diets consist largely of vegetarian foods but may include fish or poultry , or sometimes other meats , on an infrequent basis . Those with diets containing fish or poultry may define meat only as mammalian flesh and may identify with vegetarianism . A pescetarian diet has been described as `` fish but no other meat '' . The common use association between such diets and vegetarianism has led vegetarian groups such as the Vegetarian Society to state that diets containing these ingredients are not vegetarian , because fish and birds are also animals .


Venus

Venus is the second planet from the Sun , orbiting it every 224.7 Earth days . It has the longest rotation period ( 243 days ) of any planet in the Solar System and rotates in the opposite direction to most other planets . It has no natural satellites . It is named after the Roman goddess of love and beauty . It is the second-brightest natural object in the night sky after the Moon , reaching an apparent magnitude of − 4.6 , bright enough to cast shadows at night and , though rare , occasionally be visible in broad daylight . Because Venus orbits within Earth 's orbit it is an inferior planet and never appears to venture far from the Sun ; its maximum angular distance from the Sun ( elongation ) is 47.8 ° .   Venus is a terrestrial planet and is sometimes called Earth 's `` sister planet '' because of their similar size , mass , proximity to the Sun , and bulk composition . It is radically different from Earth in other respects . It has the densest atmosphere of the four terrestrial planets , consisting of more than 96 % carbon dioxide . The atmospheric pressure at the planet 's surface is 92 times that of Earth , or roughly the pressure found 900 m underwater on Earth . Venus is by far the hottest planet in the Solar System , with a mean surface temperature of 735 K , even though Mercury is closer to the Sun . Venus is shrouded by an opaque layer of highly reflective clouds of sulfuric acid , preventing its surface from being seen from space in visible light . It may have had water oceans in the past , but these would have vaporized as the temperature rose due to a runaway greenhouse effect . The water has probably photodissociated , and the free hydrogen has been swept into interplanetary space by the solar wind because of the lack of a planetary magnetic field . Venus 's surface is a dry desertscape interspersed with slab-like rocks and is periodically resurfaced by volcanism .   As one of the brightest objects in the sky , Venus has been a major fixture in human culture for as long as records have existed . It has been made sacred to gods of many cultures , and has been a prime inspiration for writers and poets as the `` morning star '' and `` evening star '' . Venus was the first planet to have its motions plotted across the sky , as early as the second millennium BC .   As the closest planet to Earth , Venus has been a prime target for early interplanetary exploration . It was the first planet beyond Earth visited by a spacecraft ( Mariner 2 in 1962 ) , and the first to be successfully landed on ( by Venera 7 in 1970 ) . Venus 's thick clouds render observation of its surface impossible in visible light , and the first detailed maps did not emerge until the arrival of the Magellan orbiter in 1991 . Plans have been proposed for rovers or more complex missions , but they are hindered by Venus 's hostile surface conditions .


Vermont

Vermont ( -LSB- vərˈmɒnt , _ vɜr - -RSB- ) is a state in the New England region of the northeastern United States . It borders the other U.S. states of Massachusetts to the south , New Hampshire to the east , New York to the west , and the Canadian province of Quebec to the north . Lake Champlain forms half of Vermont 's western border with the state of New York and the Green Mountains run north-south the length of the state .   Vermont is the 2nd-least populous of the U.S. states , ahead of Wyoming in population . The capital is Montpelier , the least populous state capital in the U.S. . The most populous municipality , Burlington , is the least populous city in the U.S. to be the most populous within a state . As of 2015 , Vermont was the leading producer of maple syrup in the U.S. . It was ranked as the safest state in the country in 2016 .   For thousands of years indigenous peoples , including the Algonquian-speaking Abenaki and Mohawk , occupied much of the territory that is now Vermont and was later claimed by France 's colony of New France . France ceded the territory to Great Britain after being defeated in 1763 in the Seven Years ' War . For many years , the nearby colonies , especially the provinces of New Hampshire and New York , disputed control of the area ( then called the New Hampshire Grants ) . Settlers who held land titles granted by New York were opposed by the Green Mountain Boys militia , which supported the many settlers whose claims were based on grants from New Hampshire .   Ultimately , those settlers prevailed in creating an independent state , the Vermont Republic . Founded in 1777 during the American Revolutionary War , the republic lasted for 14 years . Aside from the original 13 states that were formerly colonies , Vermont is one of only four U.S. states that were previously sovereign states ( along with California , Hawaii , and Texas ) . Vermont was also the first state to join the U.S. as its 14th member state after the original 13 . While still an independent republic , Vermont was the first of any future U.S. state to partially abolish slavery .


Vertical farming

Vertical farming is the practice of producing food and medicine in vertically stacked layers , vertically inclined surfaces and/or integrated in other structures ( such as in a skyscraper , used warehouse , or shipping container ) . The modern ideas of vertical farming use indoor farming techniques and controlled-environment agriculture ( CEA ) technology , where all environmental factors can be controlled . These facilities utilize artificial control of light , environmental control ( humidity , temperature , gases ... ) and fertigation . Some vertical farms use techniques similar to greenhouses , where natural sunlight can be augmented with artificial lighting and metal reflectors .


Vienna

Vienna ( -LSB- viˈɛnə -RSB- Wien , -LSB- viːn -RSB- ) is the capital and largest city of Austria and one of the nine states of Austria . Vienna is Austria 's primary city , with a population of about 1.8 million ( 2.6 million within the metropolitan area , nearly one third of Austria 's population ) , and its cultural , economic , and political centre . It is the 7th-largest city by population within city limits in the European Union . Until the beginning of the 20th century , it was the largest German-speaking city in the world , and before the splitting of the Austro-Hungarian Empire in World War I , the city had 2 million inhabitants . Today , it has the second largest number of German speakers after Berlin . Vienna is host to many major international organizations , including the United Nations and OPEC . The city is located in the eastern part of Austria and is close to the borders of the Czech Republic , Slovakia , and Hungary . These regions work together in a European Centrope border region . Along with nearby Bratislava , Vienna forms a metropolitan region with 3 million inhabitants . In 2001 , the city centre was designated a UNESCO World Heritage Site .   Apart from being regarded as the City of Music because of its musical legacy , Vienna is also said to be `` The City of Dreams '' because it was home to the world 's first psycho-analyst -- Sigmund Freud . The city 's roots lie in early Celtic and Roman settlements that transformed into a Medieval and Baroque city , and then the capital of the Austro-Hungarian Empire . It is well known for having played an essential role as a leading European music centre , from the great age of Viennese Classicism through the early part of the 20th century . The historic centre of Vienna is rich in architectural ensembles , including Baroque castles and gardens , and the late-19th-century Ringstraße lined with grand buildings , monuments and parks .   Vienna is known for its high quality of life . In a 2005 study of 127 world cities , the Economist Intelligence Unit ranked the city first ( in a tie with Vancouver , Canada and San Francisco , USA ) for the world 's most liveable cities . Between 2011 and 2015 , Vienna was ranked second , behind Melbourne , Australia .  For eight consecutive years ( 2009 -- 2016 ) , the human-resource-consulting firm Mercer ranked Vienna first in its annual `` Quality of Living '' survey of hundreds of cities around the world , a title the city still held in 2016 . Monocle 's 2015 `` Quality of Life Survey '' ranked Vienna second on a list of the top 25 cities in the world `` to make a base within . ''   The UN-Habitat has classified Vienna as being the most prosperous city in the world in 2012/2013 .  The city was ranked 1st globally for its culture of innovation in 2007 and 2008 , and sixth globally ( out of 256 cities ) in the 2014 Innovation Cities Index , which analyzed 162 indicators in covering three areas : culture , infrastructure , and markets . Vienna regularly hosts urban planning conferences and is often used as a case study by urban planners .   Between 2005 and 2010 , Vienna was the world 's number-one destination for international congresses and conventions . It attracts over 6.8 million tourists a year .


Vietnam

Vietnam ( ˌ ; -LSB- vîət nāːm -RSB- ) , officially the Socialist Republic of Vietnam ( SRV ; , is the easternmost country on the Indochina Peninsula in Southeast Asia . With an estimated 92.7 million inhabitants , it is the world 's 14th-most-populous country , and the ninth-most-populous Asian country . Vietnam is bordered by China to the north , Laos to the northwest , Cambodia to the southwest , Thailand across the Gulf of Thailand to the southwest , and the Philippines , Malaysia and Indonesia across the South China Sea to the east and southeast . Its capital city has been Hanoi since the reunification of North and South Vietnam in 1976 , with Ho Chi Minh City as a historical city as well .   The northern part of Vietnam was part of Imperial China for over a millennium , from 111 BC to AD 939 . An independent Vietnamese state was formed in 939 , following a Vietnamese victory in the Battle of Bạch Đằng River . Successive Vietnamese imperial dynasties flourished as the nation expanded geographically and politically into Southeast Asia , until the Indochina Peninsula was colonized by the French in the mid-19th century . Following a Japanese occupation in the 1940s , the Vietnamese fought French rule in the First Indochina War , eventually expelling the French in 1954 . Thereafter , Vietnam was divided politically into two rival states , North Vietnam ( officially the Democratic Republic of Vietnam ) , and South Vietnam ( officially the Republic of Vietnam ) . Conflict between the two sides intensified in what is known as the Vietnam War . The war ended with a North Vietnamese victory in 1975 .   Vietnam was then unified under a communist government but remained impoverished and politically isolated . In 1986 , the government initiated a series of economic and political reforms which began Vietnam 's path towards integration into the world economy . By 2000 , it had established diplomatic relations with all nations . Since 2000 , Vietnam 's economic growth rate has been among the highest in the world , and , in 2011 , it had the highest Global Growth Generators Index among 11 major economies . Its successful economic reforms resulted in its joining the World Trade Organization in 2007 . It is also a member of the Asia-Pacific Economic Cooperation and the Organisation Internationale de la Francophonie . Vietnam remains one of the world 's four remaining one-party socialist states officially espousing communism .


Vietnam War

The Vietnam War ( Chiến tranh Việt Nam ) , also known as the Second Indochina War , and known in Vietnam as Resistance War Against America ( Kháng chiến chống Mỹ ) or simply the American War , was a war that occurred in Vietnam , Laos , and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975 . It was the second of the Indochina Wars and was officially fought between North Vietnam and the government of South Vietnam . The North Vietnamese army was supported by the Soviet Union , China and other communist allies and the South Vietnamese army was supported by the United States , South Korea , Australia , Thailand and other anti-communist allies . The war is therefore considered a Cold War-era proxy war .   The Viet Cong ( also known as the National Liberation Front , or NLF ) , a South Vietnamese communist common front aided by the North , fought a guerrilla war against anti-communist forces in the region , while the People 's Army of Vietnam , also known as the North Vietnamese Army ( NVA ) , engaged in more conventional warfare , at times committing large units to battle . As the war continued , the military actions of the Viet Cong decreased as the role and engagement of the NVA grew . U.S. and South Vietnamese forces relied on air superiority and overwhelming firepower to conduct search and destroy operations , involving ground forces , artillery , and airstrikes . In the course of the war , the U.S. conducted a large-scale strategic bombing campaign against North Vietnam .   The North Vietnamese government and the Viet Cong were fighting to reunify Vietnam . They viewed the conflict as a colonial war and a continuation of the First Indochina War against forces from France and later on the United States . The U.S. government viewed its involvement in the war as a way to prevent a communist takeover of South Vietnam . This was part of the domino theory of a wider containment policy , with the stated aim of stopping the spread of communism worldwide .   Beginning in 1950 , American military advisors arrived in what was then French Indochina.The Military Assistance Advisory Group , Indochina ( with an authorized strength of 128 men ) was set up in September 1950 with a mission to oversee the use and distribution of US military equipment by the French and their allies . U.S. involvement escalated in the early 1960s , with troop levels tripling in 1961 and again in 1962 . U.S. involvement escalated further following the 1964 Gulf of Tonkin incident , in which a U.S. destroyer clashed with North Vietnamese fast attack craft , which was followed by the Gulf of Tonkin Resolution , which gave the U.S. president authorization to increase U.S. military presence . Regular U.S. combat units were deployed beginning in 1965 . Operations crossed international borders : bordering areas of Laos and Cambodia were heavily bombed by U.S. forces as American involvement in the war peaked in 1968 , the same year that the communist side launched the Tet Offensive . The Tet Offensive failed in its goal of overthrowing the South Vietnamese government , but became the turning point in the war , as it persuaded a large segment of the U.S. population that its government 's claims of progress toward winning the war were illusory despite many years of massive U.S. military aid to South Vietnam .   Gradual withdrawal of U.S. ground forces began as part of `` Vietnamization '' , which aimed to end American involvement in the war while transferring the task of fighting the communists to the South Vietnamese themselves . Despite the Paris Peace Accord , which was signed by all parties in January 1973 , the fighting continued . In the U.S. and the Western world , a large anti-Vietnam War movement developed as part of a larger counterculture . The war changed the dynamics between the Eastern and Western Blocs , and altered North -- South relations .   Direct U.S. military involvement ended on 15 August 1973 . The capture of Saigon by the North Vietnamese Army in April 1975 marked the end of the war , and North and South Vietnam were reunified the following year . The war exacted a huge human cost in terms of fatalities ( see Vietnam War casualties ) . Estimates of the number of Vietnamese soldiers and civilians killed vary from 966,000 to 3.8 million . Some 240,000 -- 300,000 Cambodians , 20,000 -- 62,000 Laotians , and 58,220 U.S. service members also died in the conflict , and a further 1,626 remain missing in action .


Vine

A vine ( Latin vīnea `` grapevine '' , `` vineyard '' , from vīnum `` wine '' ) in the narrowest sense is the grapevine ( Vitis ) , but more generally it can refer to any plant with a growth habit of trailing or scandent ( that is , climbing ) stems , lianas or runners . The word also can refer to such stems or runners themselves , for instance when used in wicker work .   In the United Kingdom , the term `` vine '' applies almost exclusively to the grapevine . The term `` climber '' is used for all climbing plants .


Violence

Violence is defined by the World Health Organization as `` the intentional use of physical force or power , threatened or actual , against oneself , another person , or against a group or community , which either results in or has a high likelihood of resulting in injury , death , psychological harm , maldevelopment , or deprivation '' , although the group acknowledges that the inclusion of `` the use of power '' in its definition expands on the conventional understanding of the word . This definition involves intentionality with the committing of the act itself , irrespective of the outcome it produces . However , generally , anything that is excited in an injurious or damaging way may be described as violent even if not meant to be violence ( by a person and against a person ) .   Globally , violence resulted in the deaths of an estimated 1.28 million people in 2013 up from 1.13 million in 1990 . Of the deaths in 2013 , roughly 842,000 were attributed to self-harm ( suicide ) , 405,000 to interpersonal violence , and 31,000 to collective violence ( war ) and legal intervention . In Africa , out of every 100,000 people , each year an estimated 60.9 die a violent death . Corlin , past president of the American Medical Association said : `` The United States leads the world -- in the rate at which its children die from firearms . '' He concluded : `` Gun violence is a threat to the public health of our country . '' For each single death due to violence , there are dozens of hospitalizations , hundreds of emergency department visits , and thousands of doctors ' appointments . Furthermore , violence often has lifelong consequences for physical and mental health and social functioning and can slow economic and social development .   In 2013 , assault by firearm was the leading cause of death due to interpersonal violence , with 180,000 such deaths estimated to have occurred . The same year , assault by sharp object resulted in roughly 114,000 deaths , with a remaining 110,000 deaths from personal violence being attributed to other causes .   Violence in many forms is preventable . There is a strong relationship between levels of violence and modifiable factors such as concentrated poverty , income and gender inequality , the harmful use of alcohol , and the absence of safe , stable , and nurturing relationships between children and parents . Strategies addressing the underlying causes of violence can be effective in preventing violence .


Virial expansion

The classical virial expansion expresses the pressure of a many-particle system in equilibrium as a power series in the number density .  The virial expansion , introduced in 1901 by Heike Kamerlingh Onnes , is a generalization of the ideal gas law . He wrote that for a gas containing atoms  or molecules ,   where is the pressure , is the Boltzmann constant , is the absolute temperature , and  is the number density of the  gas .  Note that for a gas containing a fraction of ( Avogadro 's number ) molecules , truncation of the virial expansion after the  first term leads to , which is the ideal gas law .   Writing , the virial expansion can be written as   .   The virial coefficients are characteristic of the interactions between the particles in the system and in general depend on the temperature . Virial expansion can also be applied to aqueous ionic solutions , as shown by Harold Friedman .


Viscosity

The viscosity of a fluid is a measure of its resistance to gradual deformation by shear stress or tensile stress . For liquids , it corresponds to the informal concept of `` thickness '' ; for example , honey has a much higher viscosity than water .   Viscosity is a property of the fluid which opposes the relative motion between the two surfaces of the fluid in a fluid that are moving at different velocities . When the fluid is forced through a tube , the particles which compose the fluid generally move more quickly near the tube 's axis and more slowly near its walls ; therefore some stress ( such as a pressure difference between the two ends of the tube ) is needed to overcome the friction between particle layers to keep the fluid moving . For a given velocity pattern , the stress required is proportional to the fluid 's viscosity .   A fluid that has no resistance to shear stress is known as an ideal or inviscid fluid . Zero viscosity is observed only at very low temperatures in superfluids . Otherwise , all fluids have positive viscosity , and are technically said to be viscous or viscid . In common parlance , however , a liquid is said to be viscous if its viscosity is substantially greater than that of water , and may be described as mobile if the viscosity is noticeably less than water . A fluid with a relatively high viscosity , such as pitch , may appear to be a solid .


Volcanism

Volcanism is the phenomenon of eruption of molten rock ( magma ) onto the surface of the Earth or a solid-surface planet or moon , where lava , pyroclastics and volcanic gases erupt through a break in the surface called a vent . It includes all phenomena resulting from and causing magma within the crust or mantle of the body , to rise through the crust and form volcanic rocks on the surface .


Volcano

A volcano is a rupture in the crust of a planetary-mass object , such as Earth , that allows hot lava , volcanic ash , and gases to escape from a magma chamber below the surface .   Earth 's volcanoes occur because its crust is broken into 17 major , rigid tectonic plates that float on a hotter , softer layer in its mantle . Therefore , on Earth , volcanoes are generally found where tectonic plates are diverging or converging , and most are found underwater . For example , a mid-oceanic ridge , such as the Mid-Atlantic Ridge , has volcanoes caused by divergent tectonic plates pulling apart ; the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates coming together . Volcanoes can also form where there is stretching and thinning of the crust 's , e.g. , in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande Rift in North America . This type of volcanism falls under the umbrella of `` plate hypothesis '' volcanism . Volcanism away from plate boundaries has also been explained as mantle plumes . These so-called `` hotspots '' , for example Hawaii , are postulated to arise from upwelling diapirs with magma from the core -- mantle boundary , 3,000 km deep in the Earth . Volcanoes are usually not created where two tectonic plates slide past one another .   Erupting volcanoes can pose many hazards , not only in the immediate vicinity of the eruption . One such hazard is that volcanic ash can be a threat to aircraft , in particular those with jet engines where ash particles can be melted by the high operating temperature ; the melted particles then adhere to the turbine blades and alter their shape , disrupting the operation of the turbine . Large eruptions can affect temperature as ash and droplets of sulfuric acid obscure the sun and cool the Earth 's lower atmosphere ( or troposphere ) ; however , they also absorb heat radiated up from the Earth , thereby warming the upper atmosphere ( or stratosphere ) . Historically , so-called volcanic winters have caused catastrophic famines .


WSEE-TV

WSEE-TV is the CBS-affiliated television station for Northwestern Pennsylvania that is licensed to Erie . It broadcasts a high definition digital signal on UHF channel 16 ( or virtual channel 35.1 via PSIP ) from a transmitter on Old Waterford Road in Greene Township . The station can also be seen on Spectrum channel 5 and in high definition on digital channel 1005 . Owned by Lilly Broadcasting , WSEE-TV operates the area 's NBC affiliate WICU-TV ( owned by SJL Broadcasting ) through a shared services agreement ( SSA ) and the two outlets share studios on State Street in Erie . Until 2017 , WSEE was also seen over-the-air in standard definition on WICU-TV 's third digital subchannel on VHF channel 12.3 from the same Greene Township transmitter .


Wallace Smith Broecker

Wallace Smith Broecker ( born November 29 , 1931 in Chicago ) is the Newberry Professor in the Department of Earth and Environmental Sciences at Columbia University , a scientist at Columbia 's Lamont-Doherty Earth Observatory and a sustainability fellow at Arizona State University . He developed the idea of a global `` conveyor belt '' linking the circulation of the global ocean and made major contributions to the science of the carbon cycle and the use of chemical tracers and isotope dating in oceanography . Broecker has received the Crafoord Prize and the Vetlesen Prize .


Walter Munk

Walter Heinrich Munk ( born October 19 , 1917 ) is an American physical oceanographer . He is professor of geophysics emeritus and holds the Secretary of the Navy/Chief of Naval Operations Oceanography Chair at Scripps Institution of Oceanography in La Jolla , California .


Waste heat

Waste heat is by necessity produced both by machines that do work and in other processes that use energy , for example in a refrigerator warming the room air or a combustion engine releasing heat into the environment . The need for many systems to reject heat as a by-product of their operation is fundamental to the laws of thermodynamics . Waste heat has lower utility ( or in thermodynamics lexicon a lower exergy or higher entropy ) than the original energy source . Sources of waste heat include all manner of human activities , natural systems , and all organisms .   Instead of being `` wasted '' by release into the ambient environment , sometimes waste heat ( or cold ) can be utilized by another process ( such as using hot engine coolant to heat a vehicle ) , or a portion of heat that would otherwise be wasted can be reused in the same process if make-up heat is added to the system ( as with heat recovery ventilation in a building ) .   Thermal energy storage , which includes technologies both for short - and long-term retention of heat or cold , can create or improve the utility of waste heat ( or cold ) . One example is waste heat from air conditioning machinery stored in a buffer tank to aid in night time heating . Another is seasonal thermal energy storage ( STES ) at a foundry in Sweden . The heat is stored in the bedrock surrounding a cluster of heat exchanger equipped boreholes , and is used for space heating in an adjacent factory as needed , even months later . An example of using STES to utilize natural waste heat is the Drake Landing Solar Community in Alberta , Canada , which , by using a cluster of boreholes in bedrock for interseasonal heat storage , obtains 97 percent of its year-round heat from solar thermal collectors on the garage roofs . Another STES application is storing winter cold underground , for summer air conditioning .   On a biological scale , all organisms reject waste heat as part of their metabolic processes , and will die if the ambient temperature is too high to allow this .   Anthropogenic waste heat is thought by some to contribute to the urban heat island effect . The biggest point sources of waste heat originate from machines ( such as electrical generators or industrial processes , such as steel or glass production ) and heat loss through building envelopes . The burning of transport fuels is a major contribution to waste heat .


Water

Water is a transparent and nearly colorless chemical substance that is the main constituent of Earth 's streams , lakes , and oceans , and the fluids of most living organisms . Its chemical formula is H2O , meaning that its molecule contains one oxygen and two hydrogen atoms , that are connected by covalent bonds . Water strictly refers to the liquid state of that substance , that prevails at standard ambient temperature and pressure ; but it often refers also to its solid state ( ice ) or its gaseous state ( steam or water vapor ) . It also occurs in nature as snow , glaciers , ice packs and icebergs , clouds , fog , dew , aquifers , and atmospheric humidity .   Water covers 71 % of the Earth 's surface . It is vital for all known forms of life . On Earth , 96.5 % of the planet 's crust water is found in seas and oceans , 1.7 % in groundwater , 1.7 % in glaciers and the ice caps of Antarctica and Greenland , a small fraction in other large water bodies , and 0.001 % in the air as vapor , clouds ( formed of ice and liquid water suspended in air ) , and precipitation . Only 2.5 % of this water is freshwater , and 98.8 % of that water is in ice ( excepting ice in clouds ) and groundwater . Less than 0.3 % of all freshwater is in rivers , lakes , and the atmosphere , and an even smaller amount of the Earth 's freshwater ( 0.003 % ) is contained within biological bodies and manufactured products . A greater quantity of water is found in the earth 's interior .   Water on Earth moves continually through the water cycle of evaporation and transpiration ( evapotranspiration ) , condensation , precipitation , and runoff , usually reaching the sea . Evaporation and transpiration contribute to the precipitation over land . Large amounts of water are also chemically combined or adsorbed in hydrated minerals .   Safe drinking water is essential to humans and other lifeforms even though it provides no calories or organic nutrients . Access to safe drinking water has improved over the last decades in almost every part of the world , but approximately one billion people still lack access to safe water and over 2.5 billion lack access to adequate sanitation . There is a clear correlation between access to safe water and gross domestic product per capita . However , some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability . A report , issued in November 2009 , suggests that by 2030 , in some developing regions of the world , water demand will exceed supply by 50 % .   Water plays an important role in the world economy . Approximately 70 % of the freshwater used by humans goes to agriculture . Fishing in salt and fresh water bodies is a major source of food for many parts of the world . Much of long-distance trade of commodities ( such as oil and natural gas ) and manufactured products is transported by boats through seas , rivers , lakes , and canals . Large quantities of water , ice , and steam are used for cooling and heating , in industry and homes . Water is an excellent solvent for a wide variety of chemical substances ; as such it is widely used in industrial processes , and in cooking and washing . Water is also central to many sports and other forms of entertainment , such as swimming , pleasure boating , boat racing , surfing , sport fishing , and diving .


Water cycle

The water cycle , also known as the hydrological cycle or the hydrologic cycle , describes the continuous movement of water on , above and below the surface of the Earth . The mass of water on Earth remains fairly constant over time but the partitioning of the water into the major reservoirs of ice , fresh water , saline water and atmospheric water is variable depending on a wide range of climatic variables . The water moves from one reservoir to another , such as from river to ocean , or from the ocean to the atmosphere , by the physical processes of evaporation , condensation , precipitation , infiltration , surface runoff , and subsurface flow . In doing so , the water goes through different forms : liquid , solid ( ice ) and vapor .   The water cycle involves the exchange of energy , which leads to temperature changes . For instance , when water evaporates , it takes up energy from its surroundings and cools the environment . When it condenses , it releases energy and warms the environment . These heat exchanges influence climate .   The evaporative phase of the cycle purifies water which then replenishes the land with freshwater . The flow of liquid water and ice transports minerals across the globe . It is also involved in reshaping the geological features of the Earth , through processes including erosion and sedimentation . The water cycle is also essential for the maintenance of most life and ecosystems on the planet .


Water heating

Water heating is a thermodynamic process that uses an energy source to heat water above its initial temperature . Typical domestic uses of hot water include cooking , cleaning , bathing , and space heating . In industry , hot water and water heated to steam have many uses .   Domestically , water is traditionally heated in vessels known as water heaters , kettles , cauldrons , pots , or coppers . These metal vessels that heat a batch of water do not produce a continual supply of heated water at a preset temperature . Rarely , hot water occurs naturally , usually from natural hot springs . The temperature varies with the consumption rate , becoming cooler as flow increases .   Appliances that provide a continual supply of hot water are called water heaters , hot water heaters , hot water tanks , boilers , heat exchangers , geysers , or calorifiers . These names depend on region , and whether they heat potable or non-potable water , are in domestic or industrial use , and their energy source . In domestic installations , potable water heated for uses other than space heating is also called domestic hot water ( DHW ) .   Fossil fuels ( natural gas , liquefied petroleum gas , oil ) , or solid fuels are commonly used for heating water . These may be consumed directly or may produce electricity that , in turn , heats water . Electricity to heat water may also come from any other electrical source , such as nuclear power or renewable energy . Alternative energy such as solar energy , heat pumps , hot water heat recycling , and geothermal heating can also heat water , often in combination with backup systems powered by fossil fuels or electricity .   Densely populated urban areas of some countries provide district heating of hot water . This is especially the case in Scandinavia and Finland . District heating systems supply energy for water heating and space heating from waste heat from industries , power plants , incinerators , geothermal heating , and central solar heating . Actual heating of tap water is performed in heat exchangers at the consumers ' premises . Generally the consumer has no in-building backup system , due to the expected high availability of district heating systems .


Water on Mars

Almost all water on Mars today exists as ice , though it also exists in small quantities as vapor in the atmosphere and occasionally as low-volume liquid brines in shallow Martian soil . The only place where water ice is visible at the surface is at the north polar ice cap . Abundant water ice is also present beneath the permanent carbon dioxide ice cap at the Martian south pole and in the shallow subsurface at more temperate latitudes . More than five million cubic kilometers of ice have been identified at or near the surface of modern Mars , enough to cover the whole planet to a depth of 35 meters . Even more ice is likely to be locked away in the deep subsurface .   Some liquid water may occur transiently on the Martian surface today , but only under certain conditions . No large standing bodies of liquid water exist , because the atmospheric pressure at the surface averages just 600 Pa -- about 0.6 % of Earth 's mean sea level pressure -- and because the global average temperature is far too low ( 210 K ) , leading to either rapid evaporation ( sublimation ) or rapid freezing . Before about 3.8 billion years ago , Mars may have had a denser atmosphere and higher surface temperatures , allowing vast amounts of liquid water on the surface , possibly including a large ocean that may have covered one-third of the planet . Water has also apparently flowed across the surface for short periods at various intervals more recently in Mars ' history . On December 9 , 2013 , NASA reported that , based on evidence from the Curiosity rover studying Aeolis Palus , Gale Crater contained an ancient freshwater lake that could have been a hospitable environment for microbial life .   Many lines of evidence indicate that water is abundant on Mars and has played a significant role in the planet 's geologic history . The present-day inventory of water on Mars can be estimated from spacecraft imagery , remote sensing techniques ( spectroscopic measurements , radar , etc. ) , and surface investigations from landers and rovers . Geologic evidence of past water includes enormous outflow channels carved by floods , ancient river valley networks , deltas , and lakebeds ; and the detection of rocks and minerals on the surface that could only have formed in liquid water . Numerous geomorphic features suggest the presence of ground ice ( permafrost ) and the movement of ice in glaciers , both in the recent past and present . Gullies and slope lineae along cliffs and crater walls suggest that flowing water continues to shape the surface of Mars , although to a far lesser degree than in the ancient past .   Although the surface of Mars was periodically wet and could have been hospitable to microbial life billions of years ago , the current environment at the surface is dry and subfreezing , probably presenting an insurmountable obstacle for living organisms . In addition , Mars lacks a thick atmosphere , ozone layer , and magnetic field , allowing solar and cosmic radiation to strike the surface unimpeded . The damaging effects of ionizing radiation on cellular structure is another one of the prime limiting factors on the survival of life on the surface . Therefore , the best potential locations for discovering life on Mars may be in subsurface environments . On November 22 , 2016 , NASA reported finding a large amount of underground ice on the planet Mars -- the volume of water detected is equivalent to the volume of water in Lake Superior .   Understanding water on Mars is vital to assess the planet 's potential for harboring life and for providing usable resources for future human exploration . For this reason , ` Follow the Water ' was the science theme of NASA 's Mars Exploration Program ( MEP ) in the first decade of the 21st century . Discoveries by the 2001 Mars Odyssey , Mars Exploration Rovers ( MERs ) , Mars Reconnaissance Orbiter ( MRO ) , and Mars Phoenix lander have been instrumental in answering key questions about water 's abundance and distribution on Mars . The ESA 's Mars Express orbiter has also provided essential data in this quest . The Mars Odyssey , Mars Express , MER Opportunity rover , MRO , and Mars Science Lander Curiosity rover are still sending back data from Mars , and discoveries continue to be made .


Water pollution

Water pollution is the contamination of water bodies ( e.g. lakes , rivers , oceans , aquifers and groundwater ) . This form of environmental degradation occurs when pollutants are directly or indirectly discharged into water bodies without adequate treatment to remove harmful compounds .   Water pollution affects the entire biosphere -- plants and organisms living in these bodies of water . In almost all cases the effect is damaging not only to individual species and population , but also to the natural biological communities .


Water scarcity

Water scarcity is the lack of sufficient available water resources to meet water needs within a region . It affects every continent and around 2.8 billion people around the world at least one month out of every year . More than 1.2 billion people lack access to clean drinking water .   Water scarcity involves water shortage , water stress or deficits , and water crisis . The relatively new concept of water stress is difficulty in obtaining sources of fresh water for use during a period of time ; it may result in further depletion and deterioration of available water resources . Water shortages may be caused by climate change , such as altered weather-patterns ( including droughts or floods ) , increased pollution , and increased human demand and overuse of water . The term water crisis labels a situation where the available potable , unpolluted water within a region is less than that region 's demand . Two converging phenomena drive water scarcity : growing freshwater use and depletion of usable freshwater resources .   Water scarcity can result from two mechanisms :   physical ( absolute ) water scarcity  economic water scarcity   Physical water scarcity results from inadequate natural water resources to supply a region 's demand , and economic water scarcity results from poor management of the sufficient available water resources . According to the United Nations Development Programme , the latter is found more often to be the cause of countries or regions experiencing water scarcity , as most countries or regions have enough water to meet household , industrial , agricultural , and environmental needs , but lack the means to provide it in an accessible manner .   Many countries and governments aim to reduce water scarcity . The UN recognizes the importance of reducing the number of people without sustainable access to clean water and sanitation . The Millennium Development Goals within the United Nations Millennium Declaration aimed by 2015 to `` halve the proportion of people who are unable to reach or to afford safe drinking water . ''


Water vapor

Water vapor , water vapour or aqueous vapor is the gaseous phase of water . It is one state of water within the hydrosphere . Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice . Unlike other forms of water , water vapor is invisible . Under typical atmospheric conditions , water vapor is continuously generated by evaporation and removed by condensation . It is lighter than air and triggers convection currents that can lead to clouds .   Being a component of Earth 's hydrosphere and hydrologic cycle , it is particularly abundant in Earth 's atmosphere where it is also a potent greenhouse gas along with other gases such as carbon dioxide and methane . Use of water vapor , as steam , has been important to humans for cooking and as a major component in energy production and transport systems since the industrial revolution .   Water vapor is a relatively common atmospheric constituent , present even in the solar atmosphere as well as every planet in the Solar System and many astronomical objects including natural satellites , comets and even large asteroids . Likewise the detection of extrasolar water vapor would indicate a similar distribution in other planetary systems . Water vapor is significant in that it can be indirect evidence supporting the presence of extraterrestrial liquid water in the case of some planetary mass objects .


Waterplace Park

Waterplace Park is an urban park situated along the Woonasquatucket River in downtown Providence , Rhode Island . Finished in 1994 , Waterplace Park is connected to 3/4 mile of cobblestone-paved pedestrian walkways along the waterfront known as Riverwalk . Venice-styled Pedestrian bridges cross the river . Most of Riverwalk is below street level and automotive traffic . Waterplace Park and Riverwalk together are host to Providence 's popular summertime Waterfire events , a series of bonfires lit on the river accompanied by classical and world music .


Watts Up With That?

Watts Up With That ? ( or WUWT ) is a blog promoting climate change denial that was created by Anthony Watts in 2006 .   The blog predominantly discusses climate issues with a focus on anthropogenic climate change , generally accommodating beliefs that are in opposition to the scientific consensus on climate change . Contributors include Christopher Monckton and Fred Singer as guest authors . In November 2009 , the blog was one of the first websites to publish emails and documents from the Climatic Research Unit controversy , and a driving force behind its coverage .   In the early months of 2010 , it was reported the site might be `` the most read climate blog in the world , '' and in 2013 Michael E. Mann referred to it as the leading climate change denial blog .


Wayback Machine

The Wayback Machine is a digital archive of the World Wide Web and other information on the Internet created by the Internet Archive , a nonprofit organization , based in San Francisco , California , United States . The Internet Archive launched the Wayback Machine in October 2001 . It was set up by Brewster Kahle and Bruce Gilliat , and is maintained with content from Alexa Internet . The service enables users to see archived versions of web pages across time , which the archive calls a `` three dimensional index '' .   Since 1996 , the Wayback Machine has been archiving cached pages of websites onto its large cluster of Linux nodes . It revisits sites every few weeks or months and archives a new version . Sites can also be captured on the fly by visitors who enter the site 's URL into a search box . The intent is to capture and archive content that otherwise would be lost whenever a site is changed or closed down . The overall vision of the machine 's creators is to archive the entire Internet .   The name Wayback Machine was chosen as a reference to the `` WABAC machine '' ( pronounced way-back ) , a time-traveling device used by the characters Mr. Peabody and Sherman in The Rocky and Bullwinkle Show , an animated cartoon . In one of the animated cartoon 's component segments , Peabody 's Improbable History , the characters routinely used the machine to witness , participate in , and , more often than not , alter famous events in history .


We Are the World

`` We Are the World '' is a song and charity single originally recorded by the supergroup United Support of Artists ( USA ) for Africa in 1985 . It was written by Michael Jackson and Lionel Richie ( with arrangements by Michael Omartian ) and produced by Quincy Jones for the album We Are the World . With sales in excess of 20 million copies , it is one of the fewer than 30 all-time physical singles to have sold at least 10 million copies worldwide .   Following Band Aid 's 1984 `` Do They Know It 's Christmas ? '' project in the United Kingdom , an idea for the creation of an American benefit single for African famine relief came from activist Harry Belafonte , who , along with fundraiser Ken Kragen , was instrumental in bringing the vision to reality . Several musicians were contacted by the pair , before Jackson and Richie were assigned the task of writing the song . The duo completed the writing of `` We Are the World '' seven weeks after the release of `` Do They Know It 's Christmas ? '' , and one night before the song 's first recording session , on January 21 , 1985 . The historic event brought together some of the most famous artists in the music industry at the time .   The song was released on March 7 , 1985 , as the only single from the album . A worldwide commercial success , it topped music charts throughout the world and became the fastest-selling American pop single in history . The first ever single to be certified multi-platinum , `` We Are the World '' received a Quadruple Platinum certification by the Recording Industry Association of America .   Awarded numerous honors -- including three Grammy Awards , one American Music Award , and a People 's Choice Award -- the song was promoted with a critically received music video , a home video , a special edition magazine , a simulcast , and several books , posters , and shirts . The promotion and merchandise aided the success of `` We Are the World '' and raised over $ 63 million ( equivalent to $ million today ) for humanitarian aid in Africa and the US .   Following the devastation caused by the magnitude 7.0 Mw earthquake in Haiti on January 12 , 2010 , a remake of the song by another all-star cast of singers was recorded on February 1 , 2010 . Entitled `` We Are the World 25 for Haiti '' , it was released as a single on February 12 , 2010 , and proceeds from the record aided survivors in the impoverished country .


We Belong Together

`` We Belong Together '' is a song by American singer Mariah Carey from her tenth studio album , The Emancipation of Mimi ( 2005 ) . The song was released on March 29 , 2005 , through Island Records , as the second single from the album . `` We Belong Together '' was written by Carey , Jermaine Dupri , Manuel Seal , and Johntá Austin , and produced by the former three . As the song samples lyrics from Bobby Womack 's `` If You Think You 're Lonely Now '' ( 1981 ) and the Deele 's `` Two Occasions '' ( 1987 ) , several other songwriters are credited . `` We Belong Together '' is built on a simple piano arrangement with an understated backbeat . The lyrics chronicle a woman 's desperation for her former lover to return .   Following her decline in popularity between 2001 and 2005 , critics dubbed the song her musical comeback , as many had considered her career over . `` We Belong Together '' earned her several music industry awards and nominations throughout 2005 -- 06 . The song broke chart records in the United States and became Carey 's sixteenth topper on the US Billboard Hot 100 . After staying at number one for fourteen non-consecutive weeks , it was placed as the second longest running number one song in US chart history , behind Carey 's own `` One Sweet Day , '' collaboration with Boyz II Men ( 1995 ) . Billboard listed it as the `` song of the decade '' and the ninth most popular song of all time . Additionally , it broke several airplay records , gathering both the largest one-day and one-week audiences in history . `` We Belong Together '' also topped the charts in Australia and reached the top two in Canada , New Zealand , and the United Kingdom .   The song 's music video was filmed as a two-part story with `` It 's Like That '' , which featured Carey at her bachelorette party . The video for `` We Belong Together '' is a continuation focusing on Carey 's wedding to an older and powerful man and ends with the singer eloping with her ex-lover . Rumors arose of the video 's connection to her 1993 marriage to Tommy Mottola . Carey performed the song on several award shows and television appearances around the world , namely MTV Movie Awards , MTV Video Music Awards , Macy 's Fourth of July Parade , The Oprah Winfrey Show and the 48th Grammy Awards . In Europe the song was performed at the Live 8 charity concert , the Fashion Rocks in Monaco , and the German Bambi Awards . Carey performed the song on both her Adventures of Mimi and Angels Advocate Tours .


We Found Love

`` We Found Love '' is a song recorded by Bajan singer Rihanna from her sixth studio album , Talk That Talk ( 2011 ) . It was written and produced by , and features Scottish DJ Calvin Harris ; the song was also featured on his third album 18 Months ( 2012 ) . `` We Found Love '' premiered on September 22 , 2011 , on the Capital FM radio station in the United Kingdom , and was made available to download on the same day as the lead single from Talk That Talk . `` We Found Love '' is an uptempo electro house song , with elements of techno and Europop . The song 's lyrics speak of a couple who `` found love in a hopeless place '' .   `` We Found Love '' was met with mixed reviews from music critics , who praised the song 's composition and Rihanna 's vocal performance ; however , some critics felt that the lyrical content was sparse and came second to Harris ' production . The song topped the US Billboard Hot 100 for ten non-consecutive weeks , becoming the longest running number-one single of 2011 . The single also surpassed `` Umbrella '' and became Rihanna 's longest running number one single . It was the singer 's eleventh song to top the Hot 100 , placing her in third place among female recording artists amassing the most number one singles . `` We Found Love '' topped the charts in twenty-five other countries including Canada , Ireland , New Zealand , Switzerland and the United Kingdom . According to Billboard it is the 24th most successful single of all time in the US . As of 2015 , the single has sold 10.5 million copies worldwide , thus being one of the best selling singles of all time . This was the first of multiple collaborations by Rihanna and Harris , including `` Where Have You Been '' and `` This Is What You Came For '' .   The song 's accompanying music video , directed by Melina Matsoukas , depicts the singer as a drug-abusing thrill-seeker in a relationship that quickly spirals downward into addiction and violence . The video received a mixed response from critics , as they noted that it profoundly alludes to ex-boyfriend Chris Brown 's assault on Rihanna , two years prior . It attracted criticism from political commentators , who questioned the video for its suggestive sexual nature . However , the video won a Grammy for `` Best Short Form Music Video '' at the 55th Annual Grammy Awards and `` Video of the Year '' at the 2012 MTV Video Music Awards . The song has been performed on both the UK and US versions of The X Factor , as well as at the 2012 Grammy Awards and the 2012 BRIT Awards . Multiple recording artists have covered `` We Found Love '' including alternative rock band Coldplay and English singer Jessie J . The song also used for the trailer of 2012 comedy-drama film Magic Mike , in the TV series Sherlock , and in the film American Honey