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13777
https://en.wikipedia.org/wiki/Hard%20disk%20drive
Hard disk drive
A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnetic material. The platters are paired with magnetic heads, usually arranged on a movi...
Technology
Data storage
null
13782
https://en.wikipedia.org/wiki/Hebrew%20calendar
Hebrew calendar
The Hebrew calendar (), also called the Jewish calendar, is a lunisolar calendar used today for Jewish religious observance and as an official calendar of Israel. It determines the dates of Jewish holidays and other rituals, such as yahrzeits and the schedule of public Torah readings. In Israel, it is used for religiou...
Technology
Calendars
null
13802
https://en.wikipedia.org/wiki/Hammer
Hammer
A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nails into wood, to shape metal (as with a forge), or to crush rock. Hammers are used for a wide range of driving, shapi...
Technology
Hand tools
null
13821
https://en.wikipedia.org/wiki/Hadron
Hadron
In particle physics, a hadron (; ) is a composite subatomic particle made of two or more quarks held together by the strong interaction. They are analogous to molecules, which are held together by the electric force. Most of the mass of ordinary matter comes from two hadrons: the proton and the neutron, while most of t...
Physical sciences
Fermions
null
13833
https://en.wikipedia.org/wiki/Hash%20table
Hash table
In computer science, a hash table is a data structure that implements an associative array, also called a dictionary or simply map; an associative array is an abstract data type that maps keys to values. A hash table uses a hash function to compute an index, also called a hash code, into an array of buckets or slots, f...
Mathematics
Data structures and types
null
13899
https://en.wikipedia.org/wiki/Harmonic%20oscillator
Harmonic oscillator
In classical mechanics, a harmonic oscillator is a system that, when displaced from its equilibrium position, experiences a restoring force F proportional to the displacement x: where k is a positive constant. If F is the only force acting on the system, the system is called a simple harmonic oscillator, and it under...
Physical sciences
Basics_10
null
13926
https://en.wikipedia.org/wiki/Hyena
Hyena
Hyenas or hyaenas ( ; from Ancient Greek , ) are feliform carnivoran mammals belonging to the family Hyaenidae (). With just four extant species (each in its own genus), it is the fifth-smallest family in the order Carnivora and one of the smallest in the class Mammalia. Despite their low diversity, hyenas are unique a...
Biology and health sciences
Carnivora
null
13974
https://en.wikipedia.org/wiki/Hymenoptera
Hymenoptera
Hymenoptera is a large order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are parasitic. Females typically have a special ovipositor for inserting eggs into hosts or places that ar...
Biology and health sciences
Hymenoptera
null
13980
https://en.wikipedia.org/wiki/Homeostasis
Homeostasis
In biology, homeostasis (British also homoeostasis; ) is the state of steady internal physical and chemical conditions maintained by living systems. This is the condition of optimal functioning for the organism and includes many variables, such as body temperature and fluid balance, being kept within certain pre-set li...
Biology and health sciences
Basics
Biology
13995
https://en.wikipedia.org/wiki/Heapsort
Heapsort
In computer science, heapsort is an efficient, comparison-based sorting algorithm that reorganizes an input array into a heap (a data structure where each node is greater than its children) and then repeatedly removes the largest node from that heap, placing it at the end of the array. Although somewhat slower in prac...
Mathematics
Algorithms
null
13996
https://en.wikipedia.org/wiki/Heap%20%28data%20structure%29
Heap (data structure)
In computer science, a heap is a tree-based data structure that satisfies the heap property: In a max heap, for any given node C, if P is the parent node of C, then the key (the value) of P is greater than or equal to the key of C. In a min heap, the key of P is less than or equal to the key of C. The node at the "top"...
Mathematics
Data structures and types
null
14004
https://en.wikipedia.org/wiki/Hour
Hour
An hour (symbol: h; also abbreviated hr) is a unit of time historically reckoned as of a day and defined contemporarily as exactly 3,600 seconds (SI). There are 60 minutes in an hour, and 24 hours in a day. The hour was initially established in the ancient Near East as a variable measure of of the night or daytime. ...
Physical sciences
Time
null
14006
https://en.wikipedia.org/wiki/Haemophilia
Haemophilia
Haemophilia (British English), or hemophilia (American English) (), is a mostly inherited genetic disorder that impairs the body's ability to make blood clots, a process needed to stop bleeding. This results in people bleeding for a longer time after an injury, easy bruising, and an increased risk of bleeding inside jo...
Biology and health sciences
Specific diseases
Health
14019
https://en.wikipedia.org/wiki/Horsepower
Horsepower
Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are the imperial horsepower as in "hp" or "bhp" which is about , and the metric hor...
Physical sciences
Power
Basics and measurement
14022
https://en.wikipedia.org/wiki/Haber%20process
Haber process
The Haber process, also called the Haber–Bosch process, is the main industrial procedure for the production of ammonia. It converts atmospheric nitrogen (N2) to ammonia (NH3) by a reaction with hydrogen (H2) using finely divided iron metal as a catalyst: This reaction is thermodynamically favorable at room temperature...
Physical sciences
Chemical reactions
null
14029
https://en.wikipedia.org/wiki/Histone
Histone
In biology, histones are highly basic proteins abundant in lysine and arginine residues that are found in eukaryotic cell nuclei and in most Archaeal phyla. They act as spools around which DNA winds to create structural units called nucleosomes. Nucleosomes in turn are wrapped into 30-nanometer fibers that form tightly...
Biology and health sciences
Proteins
Biology
14034
https://en.wikipedia.org/wiki/Heroin
Heroin
Heroin, also known as diacetylmorphine and diamorphine among other names, is a morphinan opioid substance synthesized from the dried latex of the opium poppy; it is mainly used as a recreational drug for its euphoric effects. Heroin is used medically in several countries to relieve pain, such as during childbirth or a ...
Biology and health sciences
Recreational drugs
Health
14052
https://en.wikipedia.org/wiki/Hyperbola
Hyperbola
In mathematics, a hyperbola is a type of smooth curve lying in a plane, defined by its geometric properties or by equations for which it is the solution set. A hyperbola has two pieces, called connected components or branches, that are mirror images of each other and resemble two infinite bows. The hyperbola is one of ...
Mathematics
Geometry
null
14073
https://en.wikipedia.org/wiki/Hydropower
Hydropower
Hydropower (from Ancient Greek -, "water"), also known as water power or water energy, is the use of falling or fast-running water to produce electricity or to power machines. This is achieved by converting the gravitational potential or kinetic energy of a water source to produce power. Hydropower is a method of susta...
Technology
Energy
null
14110
https://en.wikipedia.org/wiki/Holomorphic%20function
Holomorphic function
In mathematics, a holomorphic function is a complex-valued function of one or more complex variables that is complex differentiable in a neighbourhood of each point in a domain in complex coordinate space . The existence of a complex derivative in a neighbourhood is a very strong condition: It implies that a holomorphi...
Mathematics
Calculus and analysis
null
14121
https://en.wikipedia.org/wiki/Hertz
Hertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base units is s−1, meaning that one hertz is one per second or the reciprocal of one s...
Physical sciences
Electromagnetism
null
14133
https://en.wikipedia.org/wiki/Hydroponics
Hydroponics
Hydroponics is a type of horticulture and a subset of hydroculture which involves growing plants, usually crops or medicinal plants, without soil, by using water-based mineral nutrient solutions in an artificial environment. Terrestrial or aquatic plants may grow freely with their roots exposed to the nutritious liquid...
Technology
Agriculture_2
null
14136
https://en.wikipedia.org/wiki/Hydrophobe
Hydrophobe
In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly repelled from a mass of water. In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thus, prefer other neutral molecules and nonpolar solvents. Because water molecules ...
Physical sciences
Supramolecular chemistry
Chemistry
14147
https://en.wikipedia.org/wiki/Harmonic%20analysis
Harmonic analysis
Harmonic analysis is a branch of mathematics concerned with investigating the connections between a function and its representation in frequency. The frequency representation is found by using the Fourier transform for functions on unbounded domains such as the full real line or by Fourier series for functions on bound...
Mathematics
Calculus and analysis
null
14170
https://en.wikipedia.org/wiki/HIV
HIV
The human immunodeficiency viruses (HIV) are two species of Lentivirus (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive. Wit...
Biology and health sciences
Infectious disease
null
14207
https://en.wikipedia.org/wiki/Hematite
Hematite
Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . It has the same crystal structure as corundum () and ilmenite (). With this it ...
Physical sciences
Minerals
Earth science
14208
https://en.wikipedia.org/wiki/Holocene%20extinction
Holocene extinction
The Holocene extinction, also referred to as the Anthropocene extinction, is an ongoing extinction event caused by human activities during the Holocene epoch. This extinction event spans numerous families of plants and animals, including mammals, birds, reptiles, amphibians, fish, and invertebrates, impacting both terr...
Physical sciences
Events
Earth science
14225
https://en.wikipedia.org/wiki/Hydrogen%20atom
Hydrogen atom
A hydrogen atom is an atom of the chemical element hydrogen. The electrically neutral hydrogen atom contains a single positively charged proton in the nucleus, and a single negatively charged electron bound to the nucleus by the Coulomb force. Atomic hydrogen constitutes about 75% of the baryonic mass of the universe. ...
Physical sciences
s-Block
Chemistry
14229
https://en.wikipedia.org/wiki/Homeopathy
Homeopathy
Homeopathy or homoeopathy is a pseudoscientific system of alternative medicine. It was conceived in 1796 by the German physician Samuel Hahnemann. Its practitioners, called homeopaths or homeopathic physicians, believe that a substance that causes symptoms of a disease in healthy people can cure similar symptoms in sic...
Biology and health sciences
Alternative and traditional medicine
Health
14263
https://en.wikipedia.org/wiki/Horner%27s%20method
Horner's method
In mathematics and computer science, Horner's method (or Horner's scheme) is an algorithm for polynomial evaluation. Although named after William George Horner, this method is much older, as it has been attributed to Joseph-Louis Lagrange by Horner himself, and can be traced back many hundreds of years to Chinese and P...
Mathematics
Other algebra topics
null
14283
https://en.wikipedia.org/wiki/Heavy%20water
Heavy water
Heavy water (deuterium oxide, , ) is a form of water in which hydrogen atoms are all deuterium ( or D, also known as heavy hydrogen) rather than the common hydrogen-1 isotope (, also called protium) that makes up most of the hydrogen in normal water. The presence of the heavier isotope gives the water different nuclear...
Physical sciences
Water
Chemistry
14306
https://en.wikipedia.org/wiki/Hammerhead%20shark
Hammerhead shark
The hammerhead sharks are a group of sharks that form the family Sphyrnidae, named for the unusual and distinctive form of their heads, which are flattened and laterally extended into a cephalofoil (a T-shape or "hammer"). The shark's eyes are placed one on each end of this T-shaped structure, with their small mouths d...
Biology and health sciences
Sharks
null
14307
https://en.wikipedia.org/wiki/Hall%20effect
Hall effect
The Hall effect is the production of a potential difference (the Hall voltage) across an electrical conductor that is transverse to an electric current in the conductor and to an applied magnetic field perpendicular to the current. It was discovered by Edwin Hall in 1879. The Hall coefficient is defined as the ratio o...
Physical sciences
Electrodynamics
Physics
14308
https://en.wikipedia.org/wiki/Hoover%20Dam
Hoover Dam
Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona. Constructed between 1931 and 1936, during the Great Depression, it was dedicated on September 30, 1935, by President Franklin D. Roosevelt. Its construction was the result of...
Technology
Hydraulic infrastructure
null
14313
https://en.wikipedia.org/wiki/Hair
Hair
Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and fine vellus hair. Most common interest in hair is focused on hair growth, hair typ...
Biology and health sciences
Integumentary system
null
14340
https://en.wikipedia.org/wiki/Hydraulic%20ram
Hydraulic ram
A hydraulic ram pump, ram pump, or hydram is a cyclic water pump powered by hydropower. It takes in water at one "hydraulic head" (pressure) and flow rate, and outputs water at a higher hydraulic head and lower flow rate. The device uses the water hammer effect to develop pressure that allows a portion of the input wa...
Technology
Hydraulics and pneumatics
null
14347
https://en.wikipedia.org/wiki/Homininae
Homininae
Homininae (the hominines), is a subfamily of the family Hominidae (hominids). (The Homininae——encompass humans, and are also called "African hominids" or "African apes".) This subfamily includes two tribes, Hominini and Gorillini, both having extant (or living) species as well as extinct species. Tribe Hominini includ...
Biology and health sciences
Apes
Animals
14348
https://en.wikipedia.org/wiki/Homo%20habilis
Homo habilis
Homo habilis ( 'handy man') is an extinct species of archaic human from the Early Pleistocene of East and South Africa about 2.4 million years ago to 1.4 million years ago (mya). Upon species description in 1964, H. habilis was highly contested, with many researchers recommending it be synonymised with Australopithecus...
Biology and health sciences
Evolution
null
14352
https://en.wikipedia.org/wiki/Hops
Hops
Hops are the flowers (also called seed cones or strobiles) of the hop plant Humulus lupulus, a member of the Cannabaceae family of flowering plants. They are used primarily as a bittering, flavouring, and stability agent in beer, to which, in addition to bitterness, they impart floral, fruity, or citrus flavours and ar...
Biology and health sciences
Rosales
Plants
14359
https://en.wikipedia.org/wiki/Huygens%E2%80%93Fresnel%20principle
Huygens–Fresnel principle
The Huygens–Fresnel principle (named after Dutch physicist Christiaan Huygens and French physicist Augustin-Jean Fresnel) states that every point on a wavefront is itself the source of spherical wavelets, and the secondary wavelets emanating from different points mutually interfere. The sum of these spherical wavelets ...
Physical sciences
Waves
Physics
14376
https://en.wikipedia.org/wiki/Hamster
Hamster
Hamsters are rodents (order Rodentia) belonging to the subfamily Cricetinae, which contains 19 species classified in seven genera. They have become established as popular small pets. The best-known species of hamster is the golden or Syrian hamster (Mesocricetus auratus), which is the type most commonly kept as a pet. ...
Biology and health sciences
Rodents
null
14380
https://en.wikipedia.org/wiki/Helium-3
Helium-3
Helium-3 (3He see also helion) is a light, stable isotope of helium with two protons and one neutron. (In contrast, the most common isotope, helium-4, has two protons and two neutrons.) Helium-3 and protium (ordinary hydrogen) are the only stable nuclides with more protons than neutrons. It was discovered in 1939. Hel...
Physical sciences
s-Block
Chemistry
14381
https://en.wikipedia.org/wiki/Hamiltonian%20%28quantum%20mechanics%29
Hamiltonian (quantum mechanics)
In quantum mechanics, the Hamiltonian of a system is an operator corresponding to the total energy of that system, including both kinetic energy and potential energy. Its spectrum, the system's energy spectrum or its set of energy eigenvalues, is the set of possible outcomes obtainable from a measurement of the system'...
Physical sciences
Quantum mechanics
Physics
14385
https://en.wikipedia.org/wiki/Hydrolysis
Hydrolysis
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis is the cleavage of biomolecules where a water molecule is consumed to effect ...
Physical sciences
Other reactions
Chemistry
14387
https://en.wikipedia.org/wiki/Warm-blooded
Warm-blooded
Warm-blooded is a term referring to animal species whose bodies maintain a temperature higher than that of their environment. In particular, homeothermic species (including birds and mammals) maintain a stable body temperature by regulating metabolic processes. Other species have various degrees of thermoregulation. B...
Biology and health sciences
Basics
Biology
14392
https://en.wikipedia.org/wiki/Howitzer
Howitzer
The howitzer () is an artillery weapon that falls between a cannon (or field gun) and a mortar. It is capable of both low angle fire like a field gun and high angle fire like a mortar, given the distinction between low and high angle fire breaks at 45 degrees or 1600 mils (NATO). With their long-range capabilities, how...
Technology
Artillery
null
14403
https://en.wikipedia.org/wiki/Hydrogen%20peroxide
Hydrogen peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%–6% by weight) in water for consumer use and in higher concentrations for indu...
Physical sciences
Inorganic compounds
null
14413
https://en.wikipedia.org/wiki/Hydrocodone
Hydrocodone
Hydrocodone, also known as dihydrocodeinone, is a semi-synthetic opioid used to treat pain and as a cough suppressant. It is taken by mouth. Typically, it is dispensed as the combination acetaminophen/hydrocodone or ibuprofen/hydrocodone for pain severe enough to require an opioid and in combination with homatropine me...
Biology and health sciences
Pain treatments
Health
14458
https://en.wikipedia.org/wiki/Hail
Hail
Hail is a form of solid precipitation. It is distinct from ice pellets (American English "sleet"), though the two are often confused. It consists of balls or irregular lumps of ice, each of which is called a hailstone. Ice pellets generally fall in cold weather, while hail growth is greatly inhibited during low surface...
Physical sciences
Precipitation
null
14463
https://en.wikipedia.org/wiki/Harmonic%20mean
Harmonic mean
In mathematics, the harmonic mean is a kind of average, one of the Pythagorean means. It is the most appropriate average for ratios and rates such as speeds, and is normally only used for positive arguments. The harmonic mean is the reciprocal of the arithmetic mean of the reciprocals of the numbers, that is, the gen...
Mathematics
Statistics
null
14539
https://en.wikipedia.org/wiki/Internet
Internet
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a network of networks that consists of private, public, academic, business, and government networks of local to global scope, linked by a ...
Technology
Media and communication
null
14554
https://en.wikipedia.org/wiki/Imaginary%20number
Imaginary number
An imaginary number is the product of a real number and the imaginary unit , which is defined by its property . The square of an imaginary number is . For example, is an imaginary number, and its square is . The number zero is considered to be both real and imaginary. Originally coined in the 17th century by René De...
Mathematics
Basics
null
14563
https://en.wikipedia.org/wiki/Integer
Integer
An integer is the number zero (0), a positive natural number (1, 2, 3, . . .), or the negation of a positive natural number (−1, −2, −3, . . .). The negations or additive inverses of the positive natural numbers are referred to as negative integers. The set of all integers is often denoted by the boldface or blackboar...
Mathematics
Counting and numbers
null
14569
https://en.wikipedia.org/wiki/Interpolation
Interpolation
In the mathematical field of numerical analysis, interpolation is a type of estimation, a method of constructing (finding) new data points based on the range of a discrete set of known data points. In engineering and science, one often has a number of data points, obtained by sampling or experimentation, which represe...
Mathematics
Mathematical analysis
null
14587
https://en.wikipedia.org/wiki/Island
Island
An island or isle is a piece of land, distinct from a continent, completely surrounded by water. There are continental islands, which were formed by being split from a continent by plate tectonics, and oceanic islands, which have never been part of a continent. Oceanic islands can be formed from volcanic activity, grow...
Physical sciences
Terrestrial features
null
14624
https://en.wikipedia.org/wiki/Inorganic%20chemistry
Inorganic chemistry
Inorganic chemistry deals with synthesis and behavior of inorganic and organometallic compounds. This field covers chemical compounds that are not carbon-based, which are the subjects of organic chemistry. The distinction between the two disciplines is far from absolute, as there is much overlap in the subdiscipline of...
Physical sciences
Chemistry
null
14730
https://en.wikipedia.org/wiki/IRC
IRC
IRC (Internet Relay Chat) is a text-based chat system for instant messaging. IRC is designed for group communication in discussion forums, called channels, but also allows one-on-one communication via private messages as well as chat and data transfer, including file sharing. Internet Relay Chat is implemented as an a...
Technology
Internet
null
14734
https://en.wikipedia.org/wiki/Iron
Iron
Iron is a chemical element; it has the symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most abundant element in the Earth's cru...
Physical sciences
Chemistry
null
14749
https://en.wikipedia.org/wiki/Indium
Indium
Indium is a chemical element; it has symbol In and atomic number 49. It is a silvery-white post-transition metal and one of the softest elements. Chemically, indium is similar to gallium and thallium, and its properties are largely intermediate between the two. It was discovered in 1863 by Ferdinand Reich and Hieronymo...
Physical sciences
Chemical elements_2
null
14750
https://en.wikipedia.org/wiki/Iodine
Iodine
Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a violet gas at . The element was discovered by the French chemist Bernard Courtois i...
Physical sciences
Chemical elements_2
null
14752
https://en.wikipedia.org/wiki/Iridium
Iridium
Iridium is a chemical element; it has symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, it is considered the second-densest naturally occurring metal (after osmium) with a density of as defined by experimental X-ray crystallography. 191Ir and 193Ir are the only...
Physical sciences
Chemical elements_2
null
14773
https://en.wikipedia.org/wiki/Information%20theory
Information theory
Information theory is the mathematical study of the quantification, storage, and communication of information. The field was established and formalized by Claude Shannon in the 1940s, though early contributions were made in the 1920s through the works of Harry Nyquist and Ralph Hartley. It is at the intersection of ele...
Mathematics
Other
null
14775
https://en.wikipedia.org/wiki/Inch
Inch
The inch (symbol: in or ) is a unit of length in the British Imperial and the United States customary systems of measurement. It is equal to yard or of a foot. Derived from the Roman uncia ("twelfth"), the word inch is also sometimes used to translate similar units in other measurement systems, usually understood as ...
Physical sciences
Length and distance
null
14783
https://en.wikipedia.org/wiki/Erectile%20dysfunction
Erectile dysfunction
Erectile dysfunction (ED), also referred to as impotence, is a form of sexual dysfunction in males characterized by the persistent or recurring inability to achieve or maintain a penile erection with sufficient rigidity and duration for satisfactory sexual activity. It is the most common sexual problem in males and can...
Biology and health sciences
Specific diseases
Health
14810
https://en.wikipedia.org/wiki/Islamic%20calendar
Islamic calendar
The Hijri calendar (), or Arabic calendar, also known in English as the Muslim calendar and Islamic calendar, is a lunar calendar consisting of 12 lunar months in a year of 354 or 355 days. It is used to determine the proper days of Islamic holidays and rituals, such as the annual fasting and the annual season for the ...
Technology
Timekeeping
null
14828
https://en.wikipedia.org/wiki/Isomorphism
Isomorphism
In mathematics, an isomorphism is a structure-preserving mapping (a morphism) between two structures of the same type that can be reversed by an inverse mapping. Two mathematical structures are isomorphic if an isomorphism exists between them. The word is derived . The interest in isomorphisms lies in the fact that t...
Mathematics
Algebra
null
14837
https://en.wikipedia.org/wiki/Internet%20Message%20Access%20Protocol
Internet Message Access Protocol
In computing, the Internet Message Access Protocol (IMAP) is an Internet standard protocol used by email clients to retrieve email messages from a mail server over a TCP/IP connection. IMAP is defined by . IMAP was designed with the goal of permitting complete management of an email box by multiple email clients, ther...
Technology
Networks
null
14838
https://en.wikipedia.org/wiki/Inertial%20frame%20of%20reference
Inertial frame of reference
In classical physics and special relativity, an inertial frame of reference (also called an inertial space or a Galilean reference frame) is a frame of reference in which objects exhibit inertia: they remain at rest or in uniform motion relative to the frame until acted upon by external forces. In such a frame, the law...
Physical sciences
Classical mechanics
Physics
14843
https://en.wikipedia.org/wiki/Interstellar%20travel
Interstellar travel
Interstellar travel is the hypothetical travel of spacecraft between star systems. Due to the vast distances between the Solar System and nearby stars, interstellar travel is not practicable with current propulsion technologies. To travel between stars within a reasonable amount of time (decades or centuries), an inte...
Technology
Basics_6
null
14856
https://en.wikipedia.org/wiki/Inner%20product%20space
Inner product space
In mathematics, an inner product space (or, rarely, a Hausdorff pre-Hilbert space) is a real vector space or a complex vector space with an operation called an inner product. The inner product of two vectors in the space is a scalar, often denoted with angle brackets such as in . Inner products allow formal definition...
Mathematics
Linear algebra
null
14863
https://en.wikipedia.org/wiki/Incunable
Incunable
An incunable or incunabulum (: incunables or incunabula, respectively) is a book, pamphlet, or broadside that was printed in the earliest stages of printing in Europe, up to the year 1500. The specific date is essentially arbitrary, but the number of printed book editions exploded in the following century, so that all ...
Technology
Printing
null
14884
https://en.wikipedia.org/wiki/Intermediate%20value%20theorem
Intermediate value theorem
In mathematical analysis, the intermediate value theorem states that if is a continuous function whose domain contains the interval , then it takes on any given value between and at some point within the interval. This has two important corollaries: If a continuous function has values of opposite sign inside an i...
Mathematics
Real analysis
null
14895
https://en.wikipedia.org/wiki/Insulin
Insulin
Insulin (, from Latin insula, 'island') is a peptide hormone produced by beta cells of the pancreatic islets encoded in humans by the insulin (INS) gene. It is the main anabolic hormone of the body. It regulates the metabolism of carbohydrates, fats, and protein by promoting the absorption of glucose from the blood int...
Biology and health sciences
Biochemistry and molecular biology
null
14896
https://en.wikipedia.org/wiki/Inductor
Inductor
An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when an electric current flows through it. An inductor typically consists of an insulated wire wound into a coil. When the current flowing through the coil changes, the time-varyin...
Technology
Components
null
14907
https://en.wikipedia.org/wiki/Inverse%20function
Inverse function
In mathematics, the inverse function of a function (also called the inverse of ) is a function that undoes the operation of . The inverse of exists if and only if is bijective, and if it exists, is denoted by For a function , its inverse admits an explicit description: it sends each element to the unique elemen...
Mathematics
Basics
null
14909
https://en.wikipedia.org/wiki/Inertia
Inertia
Inertia is the natural tendency of objects in motion to stay in motion and objects at rest to stay at rest, unless a force causes the velocity to change. It is one of the fundamental principles in classical physics, and described by Isaac Newton in his first law of motion (also known as The Principle of Inertia). It is...
Physical sciences
Classical mechanics
null
14919
https://en.wikipedia.org/wiki/ISBN
ISBN
The International Standard Book Number (ISBN) is a numeric commercial book identifier that is intended to be unique. Publishers purchase or receive ISBNs from an affiliate of the International ISBN Agency. A different ISBN is assigned to each separate edition and variation of a publication, but not to a simple reprint...
Technology
Printing
null
14921
https://en.wikipedia.org/wiki/IP%20address
IP address
An Internet Protocol address (IP address) is a numerical label such as that is assigned to a device connected to a computer network that uses the Internet Protocol for communication. IP addresses serve two main functions: network interface identification, and location addressing. Internet Protocol version 4 (IPv4) wa...
Technology
Internet
null
14922
https://en.wikipedia.org/wiki/If%20and%20only%20if
If and only if
In logic and related fields such as mathematics and philosophy, "if and only if" (often shortened as "iff") is paraphrased by the biconditional, a logical connective between statements. The biconditional is true in two cases, where either both statements are true or both are false. The connective is biconditional (a s...
Mathematics
Mathematical logic
null
14939
https://en.wikipedia.org/wiki/Intercontinental%20ballistic%20missile
Intercontinental ballistic missile
An intercontinental ballistic missile (ICBM) is a ballistic missile with a range greater than , primarily designed for nuclear weapons delivery (delivering one or more thermonuclear warheads). Conventional, chemical, and biological weapons can also be delivered with varying effectiveness, but have never been deployed o...
Technology
Missiles
null
14946
https://en.wikipedia.org/wiki/Ice
Ice
Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 °C, 32 °F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally occurring crystalline inorganic solid with an ordered structure, ice is considered to be ...
Physical sciences
Inorganic compounds
null
14951
https://en.wikipedia.org/wiki/Ionic%20bonding
Ionic bonding
Ionic bonding is a type of chemical bonding that involves the electrostatic attraction between oppositely charged ions, or between two atoms with sharply different electronegativities, and is the primary interaction occurring in ionic compounds. It is one of the main types of bonding, along with covalent bonding and me...
Physical sciences
Chemical bonds
null
14958
https://en.wikipedia.org/wiki/Immune%20system
Immune system
The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as cancer cells, parasitic worms, and also objects such as wood splinters, distinguishing them from the organism's own healthy tissue. M...
Biology and health sciences
Biology
null
14959
https://en.wikipedia.org/wiki/Immunology
Immunology
Immunology is a branch of biology and medicine that covers the study of immune systems in all organisms. Immunology charts, measures, and contextualizes the physiological functioning of the immune system in states of both health and diseases; malfunctions of the immune system in immunological disorders (such as autoim...
Biology and health sciences
Fields of medicine
null
14968
https://en.wikipedia.org/wiki/Regular%20icosahedron
Regular icosahedron
In geometry, the regular icosahedron (or simply icosahedron) is a convex polyhedron that can be constructed from pentagonal antiprism by attaching two pentagonal pyramids with regular faces to each of its pentagonal faces, or by putting points onto the cube. The resulting polyhedron has 20 equilateral triangles as its ...
Mathematics
Three-dimensional space
null
14979
https://en.wikipedia.org/wiki/Interstellar%20cloud
Interstellar cloud
An interstellar cloud is generally an accumulation of gas, plasma, and dust in our and other galaxies. But differently, an interstellar cloud is a denser-than-average region of the interstellar medium, the matter and radiation that exists in the space between the star systems in a galaxy. Depending on the density, size...
Physical sciences
Basics_2
Astronomy
15022
https://en.wikipedia.org/wiki/Infrared
Infrared
Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with waves that are just longer than those of red light (the longest waves in the visible spectrum), so IR is invisible to t...
Physical sciences
Electrodynamics
null
15029
https://en.wikipedia.org/wiki/Industry%20Standard%20Architecture
Industry Standard Architecture
Industry Standard Architecture (ISA) is the 16-bit internal bus of IBM PC/AT and similar computers based on the Intel 80286 and its immediate successors during the 1980s. The bus was (largely) backward compatible with the 8-bit bus of the 8088-based IBM PC, including the IBM PC/XT as well as IBM PC compatibles. Origin...
Technology
Computer hardware
null
15032
https://en.wikipedia.org/wiki/IBM%20Personal%20Computer
IBM Personal Computer
The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard. Released on August 12, 1981, it was created by a team of engineers and designers at International Business Machines (IBM), directed...
Technology
Early computers
null
15043
https://en.wikipedia.org/wiki/International%20Space%20Station
International Space Station
The International Space Station (ISS) is a large space station that was assembled and is maintained in low Earth orbit by a collaboration of five space agencies and their contractors: NASA (United States), Roscosmos (Russia), ESA (Europe), JAXA (Japan), and CSA (Canada). As the largest space station ever constructed, i...
Technology
Crewed spacecraft
null
624160
https://en.wikipedia.org/wiki/Blister%20agent
Blister agent
A blister agent (or vesicant), is a chemical compound that causes severe skin, eye and mucosal pain and irritation. They are named for their ability to cause severe chemical burns, resulting in painful water blisters on the bodies of those affected. Although the term is often used in connection with large-scale burns c...
Technology
Weapon of mass destruction
null
624166
https://en.wikipedia.org/wiki/Asian%20Highway%20Network
Asian Highway Network
The Asian Highway Network (AH), also known as the Great Asian Highway, is a cooperative project among countries in Asia and the United Nations Economic and Social Commission for Asia and the Pacific (ESCAP) to improve their connectivity via highway systems, funded by G77 Gold Standards. It is one of the three pillars o...
Technology
Ground transportation networks
null
624231
https://en.wikipedia.org/wiki/Voltage%20regulator
Voltage regulator
A voltage regulator is a system designed to automatically maintain a constant voltage. It may use a simple feed-forward design or may include negative feedback. It may use an electromechanical mechanism, or electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages. Electr...
Technology
Functional circuits
null
624361
https://en.wikipedia.org/wiki/Autophagy
Autophagy
Autophagy (or autophagocytosis; from the Greek , , meaning "self-devouring" and , , meaning "hollow") is the natural, conserved degradation of the cell that removes unnecessary or dysfunctional components through a lysosome-dependent regulated mechanism. It allows the orderly degradation and recycling of cellular compo...
Biology and health sciences
Cell processes
Biology
624714
https://en.wikipedia.org/wiki/Thomson%20scattering
Thomson scattering
Thomson scattering is the elastic scattering of electromagnetic radiation by a free charged particle, as described by classical electromagnetism. It is the low-energy limit of Compton scattering: the particle's kinetic energy and photon frequency do not change as a result of the scattering. This limit is valid as long...
Physical sciences
Particle physics: General
Physics
624981
https://en.wikipedia.org/wiki/Substitution%20reaction
Substitution reaction
A substitution reaction (also known as single displacement reaction or single substitution reaction) is a chemical reaction during which one functional group in a chemical compound is replaced by another functional group. Substitution reactions are of prime importance in organic chemistry. Substitution reactions in org...
Physical sciences
Chemical reactions
null
625220
https://en.wikipedia.org/wiki/Proglacial%20lake
Proglacial lake
In geology, a proglacial lake is a lake formed either by the damming action of a moraine during the retreat of a melting glacier, a glacial ice dam, or by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ice. At the end of the last ice age about 10,000 years ago, large proglaci...
Physical sciences
Hydrology
Earth science
625226
https://en.wikipedia.org/wiki/Reversible%20reaction
Reversible reaction
A reversible reaction is a reaction in which the conversion of reactants to products and the conversion of products to reactants occur simultaneously. \mathit aA{} + \mathit bB <=> \mathit cC{} + \mathit dD A and B can react to form C and D or, in the reverse reaction, C and D can react to form A and B. This is dist...
Physical sciences
Basics_3
Chemistry
625229
https://en.wikipedia.org/wiki/Adipocyte
Adipocyte
Adipocytes, also known as lipocytes and fat cells, are the cells that primarily compose adipose tissue, specialized in storing energy as fat. Adipocytes are derived from mesenchymal stem cells which give rise to adipocytes through adipogenesis. In cell culture, adipocyte progenitors can also form osteoblasts, myocytes...
Biology and health sciences
Tissues
Biology
625232
https://en.wikipedia.org/wiki/Skeletal%20formula
Skeletal formula
The skeletal formula, line-angle formula, bond-line formula or shorthand formula of an organic compound is a type of molecular structural formula that serves as a shorthand representation of a molecule's bonding and some details of its molecular geometry. A skeletal formula shows the skeletal structure or skeleton of a...
Physical sciences
Concepts_2
Chemistry