Phonology is often distinguished from phonetics. While phonetics concerns the physical production, acoustic transmission and perception of the sounds of speech, phonology describes the way sounds function within a given language or across languages to encode meaning. For many linguists, phonetics belongs to descriptive linguistics, and phonology to theoretical linguistics, although establishing the phonological system of a language is necessarily an application of theoretical principles to analysis of phonetic evidence. Note that this distinction was not always made, particularly before the development of the modern concept of the phoneme in the mid 20th century. Some subfields of modern phonology have a crossover with phonetics in descriptive disciplines such as psycholinguistics and speech perception, resulting in specific areas like articulatory phonology or laboratory phonology.


The word phonology comes from the Greek φωνή, phōnḗ, "voice, sound," and the suffix -logy (which is from Greek λόγος, lógos, "word, speech, subject of discussion"). Definitions of the term vary. Nikolai Trubetzkoy in Grundzüge der Phonologie (1939) defines phonology as "the study of sound pertaining to the system of language," as opposed to phonetics, which is "the study of sound pertaining to the act of speech" (the distinction between language and speech being basically Saussure's distinction between langue and parole). More recently, Lass (1998) writes that phonology refers broadly to the subdiscipline of linguistics concerned with the sounds of language, while in more narrow terms, "phonology proper is concerned with the function, behavior and organization of sounds as linguistic items." According to Clark et al. (2007), it means the systematic use of sound to encode meaning in any spoken human language, or the field of linguistics studying this use.


The history of phonology may be traced back to the Ashtadhyayi, the Sanskrit grammar composed by Pāṇini in the 4th century BC. In particular the Shiva Sutras, an auxiliary text to the Ashtadhyayi, introduces what can be considered a list of the phonemes of the Sanskrit language, with a notational system for them that is used throughout the main text, which deals with matters of morphology, syntax and semantics.


The Polish scholar Jan Baudouin de Courtenay (together with his former student Mikołaj Kruszewski) introduced the concept of the phoneme in 1876, and his work, though often unacknowledged, is considered to be the starting point of modern phonology. He also worked on the theory of phonetic alternations (what is now called allophony and morphophonology), and had a significant influence on the work of Ferdinand de Saussure.


An influential school of phonology in the interwar period was the Prague school. One of its leading members was Prince Nikolai Trubetzkoy, whose Grundzüge der Phonologie (Principles of Phonology), published posthumously in 1939, is among the most important works in the field from this period. Directly influenced by Baudouin de Courtenay, Trubetzkoy is considered the founder of morphophonology, although this concept had also been recognized by de Courtenay. Trubetzkoy also developed the concept of the archiphoneme. Another important figure in the Prague school was Roman Jakobson, who was one of the most prominent linguists of the 20th century.


In 1968 Noam Chomsky and Morris Halle published The Sound Pattern of English (SPE), the basis for generative phonology. In this view, phonological representations are sequences of segments made up of distinctive features. These features were an expansion of earlier work by Roman Jakobson, Gunnar Fant, and Morris Halle. The features describe aspects of articulation and perception, are from a universally fixed set, and have the binary values + or −. There are at least two levels of representation: underlying representation and surface phonetic representation. Ordered phonological rules govern how underlying representation is transformed into the actual pronunciation (the so-called surface form). An important consequence of the influence SPE had on phonological theory was the downplaying of the syllable and the emphasis on segments. Furthermore, the generativists folded morphophonology into phonology, which both solved and created problems.


Natural phonology is a theory based on the publications of its proponent David Stampe in 1969 and (more explicitly) in 1979. In this view, phonology is based on a set of universal phonological processes that interact with one another; which ones are active and which are suppressed is language-specific. Rather than acting on segments, phonological processes act on distinctive features within prosodic groups. Prosodic groups can be as small as a part of a syllable or as large as an entire utterance. Phonological processes are unordered with respect to each other and apply simultaneously (though the output of one process may be the input to another). The second most prominent natural phonologist is Patricia Donegan (Stampe's wife); there are many natural phonologists in Europe, and a few in the U.S., such as Geoffrey Nathan. The principles of natural phonology were extended to morphology by Wolfgang U. Dressler, who founded natural morphology.


In 1976 John Goldsmith introduced autosegmental phonology. Phonological phenomena are no longer seen as operating on one linear sequence of segments, called phonemes or feature combinations, but rather as involving some parallel sequences of features which reside on multiple tiers. Autosegmental phonology later evolved into feature geometry, which became the standard theory of representation for theories of the organization of phonology as different as lexical phonology and optimality theory.


Government phonology, which originated in the early 1980s as an attempt to unify theoretical notions of syntactic and phonological structures, is based on the notion that all languages necessarily follow a small set of principles and vary according to their selection of certain binary parameters. That is, all languages' phonological structures are essentially the same, but there is restricted variation that accounts for differences in surface realizations. Principles are held to be inviolable, though parameters may sometimes come into conflict. Prominent figures in this field include Jonathan Kaye, Jean Lowenstamm, Jean-Roger Vergnaud, Monik Charette, and John Harris.


In a course at the LSA summer institute in 1991, Alan Prince and Paul Smolensky developed optimality theory—an overall architecture for phonology according to which languages choose a pronunciation of a word that best satisfies a list of constraints ordered by importance; a lower-ranked constraint can be violated when the violation is necessary in order to obey a higher-ranked constraint. The approach was soon extended to morphology by John McCarthy and Alan Prince, and has become a dominant trend in phonology. The appeal to phonetic grounding of constraints and representational elements (e.g. features) in various approaches has been criticized by proponents of 'substance-free phonology', especially Mark Hale and Charles Reiss.


Broadly speaking, government phonology (or its descendant, strict-CV phonology) has a greater following in the United Kingdom, whereas optimality theory is predominant in the United States.[citation needed]


An integrated approach to phonological theory that combines synchronic and diachronic accounts to sound patterns was initiated with Evolutionary Phonology in recent years.


An important part of traditional, pre-generative schools of phonology is studying which sounds can be grouped into distinctive units within a language; these units are known as phonemes. For example, in English, the "p" sound in pot is aspirated (pronounced [pʰ]) while that in spot is not aspirated (pronounced [p]). However, English speakers intuitively treat both sounds as variations (allophones) of the same phonological category, that is of the phoneme /p/. (Traditionally, it would be argued that if an aspirated [pʰ] were interchanged with the unaspirated [p] in spot, native speakers of English would still hear the same words; that is, the two sounds are perceived as "the same" /p/.) In some other languages, however, these two sounds are perceived as different, and they are consequently assigned to different phonemes. For example, in Thai, Hindi, and Quechua, there are minimal pairs of words for which aspiration is the only contrasting feature (two words can have different meanings but with the only difference in pronunciation being that one has an aspirated sound where the other has an unaspirated one).


Part of the phonological study of a language therefore involves looking at data (phonetic transcriptions of the speech of native speakers) and trying to deduce what the underlying phonemes are and what the sound inventory of the language is. The presence or absence of minimal pairs, as mentioned above, is a frequently used criterion for deciding whether two sounds should be assigned to the same phoneme. However, other considerations often need to be taken into account as well.


The particular contrasts which are phonemic in a language can change over time. At one time, [f] and [v], two sounds that have the same place and manner of articulation and differ in voicing only, were allophones of the same phoneme in English, but later came to belong to separate phonemes. This is one of the main factors of historical change of languages as described in historical linguistics.


The findings and insights of speech perception and articulation research complicate the traditional and somewhat intuitive idea of interchangeable allophones being perceived as the same phoneme. First, interchanged allophones of the same phoneme can result in unrecognizable words. Second, actual speech, even at a word level, is highly co-articulated, so it is problematic to expect to be able to splice words into simple segments without affecting speech perception.


Different linguists therefore take different approaches to the problem of assigning sounds to phonemes. For example, they differ in the extent to which they require allophones to be phonetically similar. There are also differing ideas as to whether this grouping of sounds is purely a tool for linguistic analysis, or reflects an actual process in the way the human brain processes a language.


Since the early 1960s, theoretical linguists have moved away from the traditional concept of a phoneme, preferring to consider basic units at a more abstract level, as a component of morphemes; these units can be called morphophonemes, and analysis using this approach is called morphophonology.


In addition to the minimal units that can serve the purpose of differentiating meaning (the phonemes), phonology studies how sounds alternate, i.e. replace one another in different forms of the same morpheme (allomorphs), as well as, for example, syllable structure, stress, feature geometry, accent, and intonation.


Phonology also includes topics such as phonotactics (the phonological constraints on what sounds can appear in what positions in a given language) and phonological alternation (how the pronunciation of a sound changes through the application of phonological rules, sometimes in a given order which can be feeding or bleeding,) as well as prosody, the study of suprasegmentals and topics such as stress and intonation.


The principles of phonological analysis can be applied independently of modality because they are designed to serve as general analytical tools, not language-specific ones. The same principles have been applied to the analysis of sign languages (see Phonemes in sign languages), even though the sub-lexical units are not instantiated as speech sounds.


Conventionally, a computer consists of at least one processing element, typically a central processing unit (CPU), and some form of memory. The processing element carries out arithmetic and logic operations, and a sequencing and control unit can change the order of operations in response to stored information. Peripheral devices allow information to be retrieved from an external source, and the result of operations saved and retrieved.


Mechanical analog computers started appearing in the first century and were later used in the medieval era for astronomical calculations. In World War II, mechanical analog computers were used for specialized military applications such as calculating torpedo aiming. During this time the first electronic digital computers were developed. Originally they were the size of a large room, consuming as much power as several hundred modern personal computers (PCs).


Modern computers based on integrated circuits are millions to billions of times more capable than the early machines, and occupy a fraction of the space. Computers are small enough to fit into mobile devices, and mobile computers can be powered by small batteries. Personal computers in their various forms are icons of the Information Age and are generally considered as "computers". However, the embedded computers found in many devices from MP3 players to fighter aircraft and from electronic toys to industrial robots are the most numerous.


The first known use of the word "computer" was in 1613 in a book called The Yong Mans Gleanings by English writer Richard Braithwait: "I haue read the truest computer of Times, and the best Arithmetician that euer breathed, and he reduceth thy dayes into a short number." It referred to a person who carried out calculations, or computations. The word continued with the same meaning until the middle of the 20th century. From the end of the 19th century the word began to take on its more familiar meaning, a machine that carries out computations.


Devices have been used to aid computation for thousands of years, mostly using one-to-one correspondence with fingers. The earliest counting device was probably a form of tally stick. Later record keeping aids throughout the Fertile Crescent included calculi (clay spheres, cones, etc.) which represented counts of items, probably livestock or grains, sealed in hollow unbaked clay containers. The use of counting rods is one example.


The abacus was initially used for arithmetic tasks. The Roman abacus was used in Babylonia as early as 2400 BC. Since then, many other forms of reckoning boards or tables have been invented. In a medieval European counting house, a checkered cloth would be placed on a table, and markers moved around on it according to certain rules, as an aid to calculating sums of money.


The Antikythera mechanism is believed to be the earliest mechanical analog "computer", according to Derek J. de Solla Price. It was designed to calculate astronomical positions. It was discovered in 1901 in the Antikythera wreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to circa 100 BC. Devices of a level of complexity comparable to that of the Antikythera mechanism would not reappear until a thousand years later.


Many mechanical aids to calculation and measurement were constructed for astronomical and navigation use. The planisphere was a star chart invented by Abū Rayhān al-Bīrūnī in the early 11th century. The astrolabe was invented in the Hellenistic world in either the 1st or 2nd centuries BC and is often attributed to Hipparchus. A combination of the planisphere and dioptra, the astrolabe was effectively an analog computer capable of working out several different kinds of problems in spherical astronomy. An astrolabe incorporating a mechanical calendar computer and gear-wheels was invented by Abi Bakr of Isfahan, Persia in 1235. Abū Rayhān al-Bīrūnī invented the first mechanical geared lunisolar calendar astrolabe, an early fixed-wired knowledge processing machine with a gear train and gear-wheels, circa 1000 AD.


The sector, a calculating instrument used for solving problems in proportion, trigonometry, multiplication and division, and for various functions, such as squares and cube roots, was developed in the late 16th century and found application in gunnery, surveying and navigation.


The slide rule was invented around 1620–1630, shortly after the publication of the concept of the logarithm. It is a hand-operated analog computer for doing multiplication and division. As slide rule development progressed, added scales provided reciprocals, squares and square roots, cubes and cube roots, as well as transcendental functions such as logarithms and exponentials, circular and hyperbolic trigonometry and other functions. Aviation is one of the few fields where slide rules are still in widespread use, particularly for solving time–distance problems in light aircraft. To save space and for ease of reading, these are typically circular devices rather than the classic linear slide rule shape. A popular example is the E6B.


In the 1770s Pierre Jaquet-Droz, a Swiss watchmaker, built a mechanical doll (automata) that could write holding a quill pen. By switching the number and order of its internal wheels different letters, and hence different messages, could be produced. In effect, it could be mechanically "programmed" to read instructions. Along with two other complex machines, the doll is at the Musée d'Art et d'Histoire of Neuchâtel, Switzerland, and still operates.


The tide-predicting machine invented by Sir William Thomson in 1872 was of great utility to navigation in shallow waters. It used a system of pulleys and wires to automatically calculate predicted tide levels for a set period at a particular location.


The differential analyser, a mechanical analog computer designed to solve differential equations by integration, used wheel-and-disc mechanisms to perform the integration. In 1876 Lord Kelvin had already discussed the possible construction of such calculators, but he had been stymied by the limited output torque of the ball-and-disk integrators. In a differential analyzer, the output of one integrator drove the input of the next integrator, or a graphing output. The torque amplifier was the advance that allowed these machines to work. Starting in the 1920s, Vannevar Bush and others developed mechanical differential analyzers.


Charles Babbage, an English mechanical engineer and polymath, originated the concept of a programmable computer. Considered the "father of the computer", he conceptualized and invented the first mechanical computer in the early 19th century. After working on his revolutionary difference engine, designed to aid in navigational calculations, in 1833 he realized that a much more general design, an Analytical Engine, was possible. The input of programs and data was to be provided to the machine via punched cards, a method being used at the time to direct mechanical looms such as the Jacquard loom. For output, the machine would have a printer, a curve plotter and a bell. The machine would also be able to punch numbers onto cards to be read in later. The Engine incorporated an arithmetic logic unit, control flow in the form of conditional branching and loops, and integrated memory, making it the first design for a general-purpose computer that could be described in modern terms as Turing-complete.


The machine was about a century ahead of its time. All the parts for his machine had to be made by hand — this was a major problem for a device with thousands of parts. Eventually, the project was dissolved with the decision of the British Government to cease funding. Babbage's failure to complete the analytical engine can be chiefly attributed to difficulties not only of politics and financing, but also to his desire to develop an increasingly sophisticated computer and to move ahead faster than anyone else could follow. Nevertheless, his son, Henry Babbage, completed a simplified version of the analytical engine's computing unit (the mill) in 1888. He gave a successful demonstration of its use in computing tables in 1906.


The first modern analog computer was a tide-predicting machine, invented by Sir William Thomson in 1872. The differential analyser, a mechanical analog computer designed to solve differential equations by integration using wheel-and-disc mechanisms, was conceptualized in 1876 by James Thomson, the brother of the more famous Lord Kelvin.


The art of mechanical analog computing reached its zenith with the differential analyzer, built by H. L. Hazen and Vannevar Bush at MIT starting in 1927. This built on the mechanical integrators of James Thomson and the torque amplifiers invented by H. W. Nieman. A dozen of these devices were built before their obsolescence became obvious.


By the 1950s the success of digital electronic computers had spelled the end for most analog computing machines, but analog computers remain in use in some specialized applications such as education (control systems) and aircraft (slide rule).


The principle of the modern computer was first described by mathematician and pioneering computer scientist Alan Turing, who set out the idea in his seminal 1936 paper, On Computable Numbers. Turing reformulated Kurt Gödel's 1931 results on the limits of proof and computation, replacing Gödel's universal arithmetic-based formal language with the formal and simple hypothetical devices that became known as Turing machines. He proved that some such machine would be capable of performing any conceivable mathematical computation if it were representable as an algorithm. He went on to prove that there was no solution to the Entscheidungsproblem by first showing that the halting problem for Turing machines is undecidable: in general, it is not possible to decide algorithmically whether a given Turing machine will ever halt.


He also introduced the notion of a 'Universal Machine' (now known as a Universal Turing machine), with the idea that such a machine could perform the tasks of any other machine, or in other words, it is provably capable of computing anything that is computable by executing a program stored on tape, allowing the machine to be programmable. Von Neumann acknowledged that the central concept of the modern computer was due to this paper. Turing machines are to this day a central object of study in theory of computation. Except for the limitations imposed by their finite memory stores, modern computers are said to be Turing-complete, which is to say, they have algorithm execution capability equivalent to a universal Turing machine.


By 1938 the United States Navy had developed an electromechanical analog computer small enough to use aboard a submarine. This was the Torpedo Data Computer, which used trigonometry to solve the problem of firing a torpedo at a moving target. During World War II similar devices were developed in other countries as well.


Early digital computers were electromechanical; electric switches drove mechanical relays to perform the calculation. These devices had a low operating speed and were eventually superseded by much faster all-electric computers, originally using vacuum tubes. The Z2, created by German engineer Konrad Zuse in 1939, was one of the earliest examples of an electromechanical relay computer.


In 1941, Zuse followed his earlier machine up with the Z3, the world's first working electromechanical programmable, fully automatic digital computer. The Z3 was built with 2000 relays, implementing a 22 bit word length that operated at a clock frequency of about 5–10 Hz. Program code was supplied on punched film while data could be stored in 64 words of memory or supplied from the keyboard. It was quite similar to modern machines in some respects, pioneering numerous advances such as floating point numbers. Replacement of the hard-to-implement decimal system (used in Charles Babbage's earlier design) by the simpler binary system meant that Zuse's machines were easier to build and potentially more reliable, given the technologies available at that time. The Z3 was Turing complete.


Purely electronic circuit elements soon replaced their mechanical and electromechanical equivalents, at the same time that digital calculation replaced analog. The engineer Tommy Flowers, working at the Post Office Research Station in London in the 1930s, began to explore the possible use of electronics for the telephone exchange. Experimental equipment that he built in 1934 went into operation 5 years later, converting a portion of the telephone exchange network into an electronic data processing system, using thousands of vacuum tubes. In the US, John Vincent Atanasoff and Clifford E. Berry of Iowa State University developed and tested the Atanasoff–Berry Computer (ABC) in 1942, the first "automatic electronic digital computer". This design was also all-electronic and used about 300 vacuum tubes, with capacitors fixed in a mechanically rotating drum for memory.


During World War II, the British at Bletchley Park achieved a number of successes at breaking encrypted German military communications. The German encryption machine, Enigma, was first attacked with the help of the electro-mechanical bombes. To crack the more sophisticated German Lorenz SZ 40/42 machine, used for high-level Army communications, Max Newman and his colleagues commissioned Flowers to build the Colossus. He spent eleven months from early February 1943 designing and building the first Colossus. After a functional test in December 1943, Colossus was shipped to Bletchley Park, where it was delivered on 18 January 1944 and attacked its first message on 5 February.


Colossus was the world's first electronic digital programmable computer. It used a large number of valves (vacuum tubes). It had paper-tape input and was capable of being configured to perform a variety of boolean logical operations on its data, but it was not Turing-complete. Nine Mk II Colossi were built (The Mk I was converted to a Mk II making ten machines in total). Colossus Mark I contained 1500 thermionic valves (tubes), but Mark II with 2400 valves, was both 5 times faster and simpler to operate than Mark 1, greatly speeding the decoding process.


The US-built ENIAC (Electronic Numerical Integrator and Computer) was the first electronic programmable computer built in the US. Although the ENIAC was similar to the Colossus it was much faster and more flexible. It was unambiguously a Turing-complete device and could compute any problem that would fit into its memory. Like the Colossus, a "program" on the ENIAC was defined by the states of its patch cables and switches, a far cry from the stored program electronic machines that came later. Once a program was written, it had to be mechanically set into the machine with manual resetting of plugs and switches.


It combined the high speed of electronics with the ability to be programmed for many complex problems. It could add or subtract 5000 times a second, a thousand times faster than any other machine. It also had modules to multiply, divide, and square root. High speed memory was limited to 20 words (about 80 bytes). Built under the direction of John Mauchly and J. Presper Eckert at the University of Pennsylvania, ENIAC's development and construction lasted from 1943 to full operation at the end of 1945. The machine was huge, weighing 30 tons, using 200 kilowatts of electric power and contained over 18,000 vacuum tubes, 1,500 relays, and hundreds of thousands of resistors, capacitors, and inductors.


Early computing machines had fixed programs. Changing its function required the re-wiring and re-structuring of the machine. With the proposal of the stored-program computer this changed. A stored-program computer includes by design an instruction set and can store in memory a set of instructions (a program) that details the computation. The theoretical basis for the stored-program computer was laid by Alan Turing in his 1936 paper. In 1945 Turing joined the National Physical Laboratory and began work on developing an electronic stored-program digital computer. His 1945 report ‘Proposed Electronic Calculator’ was the first specification for such a device. John von Neumann at the University of Pennsylvania, also circulated his First Draft of a Report on the EDVAC in 1945.


The Manchester Small-Scale Experimental Machine, nicknamed Baby, was the world's first stored-program computer. It was built at the Victoria University of Manchester by Frederic C. Williams, Tom Kilburn and Geoff Tootill, and ran its first program on 21 June 1948. It was designed as a testbed for the Williams tube the first random-access digital storage device. Although the computer was considered "small and primitive" by the standards of its time, it was the first working machine to contain all of the elements essential to a modern electronic computer. As soon as the SSEM had demonstrated the feasibility of its design, a project was initiated at the university to develop it into a more usable computer, the Manchester Mark 1.


The Mark 1 in turn quickly became the prototype for the Ferranti Mark 1, the world's first commercially available general-purpose computer. Built by Ferranti, it was delivered to the University of Manchester in February 1951. At least seven of these later machines were delivered between 1953 and 1957, one of them to Shell labs in Amsterdam. In October 1947, the directors of British catering company J. Lyons & Company decided to take an active role in promoting the commercial development of computers. The LEO I computer became operational in April 1951  and ran the world's first regular routine office computer job.


The bipolar transistor was invented in 1947. From 1955 onwards transistors replaced vacuum tubes in computer designs, giving rise to the "second generation" of computers. Compared to vacuum tubes, transistors have many advantages: they are smaller, and require less power than vacuum tubes, so give off less heat. Silicon junction transistors were much more reliable than vacuum tubes and had longer, indefinite, service life. Transistorized computers could contain tens of thousands of binary logic circuits in a relatively compact space.


At the University of Manchester, a team under the leadership of Tom Kilburn designed and built a machine using the newly developed transistors instead of valves. Their first transistorised computer and the first in the world, was operational by 1953, and a second version was completed there in April 1955. However, the machine did make use of valves to generate its 125 kHz clock waveforms and in the circuitry to read and write on its magnetic drum memory, so it was not the first completely transistorized computer. That distinction goes to the Harwell CADET of 1955, built by the electronics division of the Atomic Energy Research Establishment at Harwell.


The next great advance in computing power came with the advent of the integrated circuit. The idea of the integrated circuit was first conceived by a radar scientist working for the Royal Radar Establishment of the Ministry of Defence, Geoffrey W.A. Dummer. Dummer presented the first public description of an integrated circuit at the Symposium on Progress in Quality Electronic Components in Washington, D.C. on 7 May 1952.


The first practical ICs were invented by Jack Kilby at Texas Instruments and Robert Noyce at Fairchild Semiconductor. Kilby recorded his initial ideas concerning the integrated circuit in July 1958, successfully demonstrating the first working integrated example on 12 September 1958. In his patent application of 6 February 1959, Kilby described his new device as "a body of semiconductor material ... wherein all the components of the electronic circuit are completely integrated". Noyce also came up with his own idea of an integrated circuit half a year later than Kilby. His chip solved many practical problems that Kilby's had not. Produced at Fairchild Semiconductor, it was made of silicon, whereas Kilby's chip was made of germanium.


This new development heralded an explosion in the commercial and personal use of computers and led to the invention of the microprocessor. While the subject of exactly which device was the first microprocessor is contentious, partly due to lack of agreement on the exact definition of the term "microprocessor", it is largely undisputed that the first single-chip microprocessor was the Intel 4004, designed and realized by Ted Hoff, Federico Faggin, and Stanley Mazor at Intel.


With the continued miniaturization of computing resources, and advancements in portable battery life, portable computers grew in popularity in the 2000s. The same developments that spurred the growth of laptop computers and other portable computers allowed manufacturers to integrate computing resources into cellular phones. These so-called smartphones and tablets run on a variety of operating systems and have become the dominant computing device on the market, with manufacturers reporting having shipped an estimated 237 million devices in 2Q 2013.


In practical terms, a computer program may be just a few instructions or extend to many millions of instructions, as do the programs for word processors and web browsers for example. A typical modern computer can execute billions of instructions per second (gigaflops) and rarely makes a mistake over many years of operation. Large computer programs consisting of several million instructions may take teams of programmers years to write, and due to the complexity of the task almost certainly contain errors.


Program execution might be likened to reading a book. While a person will normally read each word and line in sequence, they may at times jump back to an earlier place in the text or skip sections that are not of interest. Similarly, a computer may sometimes go back and repeat the instructions in some section of the program over and over again until some internal condition is met. This is called the flow of control within the program and it is what allows the computer to perform tasks repeatedly without human intervention.


In most computers, individual instructions are stored as machine code with each instruction being given a unique number (its operation code or opcode for short). The command to add two numbers together would have one opcode; the command to multiply them would have a different opcode, and so on. The simplest computers are able to perform any of a handful of different instructions; the more complex computers have several hundred to choose from, each with a unique numerical code. Since the computer's memory is able to store numbers, it can also store the instruction codes. This leads to the important fact that entire programs (which are just lists of these instructions) can be represented as lists of numbers and can themselves be manipulated inside the computer in the same way as numeric data. The fundamental concept of storing programs in the computer's memory alongside the data they operate on is the crux of the von Neumann, or stored program[citation needed], architecture. In some cases, a computer might store some or all of its program in memory that is kept separate from the data it operates on. This is called the Harvard architecture after the Harvard Mark I computer. Modern von Neumann computers display some traits of the Harvard architecture in their designs, such as in CPU caches.


While it is possible to write computer programs as long lists of numbers (machine language) and while this technique was used with many early computers, it is extremely tedious and potentially error-prone to do so in practice, especially for complicated programs. Instead, each basic instruction can be given a short name that is indicative of its function and easy to remember – a mnemonic such as ADD, SUB, MULT or JUMP. These mnemonics are collectively known as a computer's assembly language. Converting programs written in assembly language into something the computer can actually understand (machine language) is usually done by a computer program called an assembler.


Programming languages provide various ways of specifying programs for computers to run. Unlike natural languages, programming languages are designed to permit no ambiguity and to be concise. They are purely written languages and are often difficult to read aloud. They are generally either translated into machine code by a compiler or an assembler before being run, or translated directly at run time by an interpreter. Sometimes programs are executed by a hybrid method of the two techniques.


Machine languages and the assembly languages that represent them (collectively termed low-level programming languages) tend to be unique to a particular type of computer. For instance, an ARM architecture computer (such as may be found in a PDA or a hand-held videogame) cannot understand the machine language of an Intel Pentium or the AMD Athlon 64 computer that might be in a PC.


Though considerably easier than in machine language, writing long programs in assembly language is often difficult and is also error prone. Therefore, most practical programs are written in more abstract high-level programming languages that are able to express the needs of the programmer more conveniently (and thereby help reduce programmer error). High level languages are usually "compiled" into machine language (or sometimes into assembly language and then into machine language) using another computer program called a compiler. High level languages are less related to the workings of the target computer than assembly language, and more related to the language and structure of the problem(s) to be solved by the final program. It is therefore often possible to use different compilers to translate the same high level language program into the machine language of many different types of computer. This is part of the means by which software like video games may be made available for different computer architectures such as personal computers and various video game consoles.


These 4G languages are less procedural than 3G languages. The benefit of 4GL is that it provides ways to obtain information without requiring the direct help of a programmer. Example of 4GL is SQL.


Errors in computer programs are called "bugs". They may be benign and not affect the usefulness of the program, or have only subtle effects. But in some cases, they may cause the program or the entire system to "hang", becoming unresponsive to input such as mouse clicks or keystrokes, to completely fail, or to crash. Otherwise benign bugs may sometimes be harnessed for malicious intent by an unscrupulous user writing an exploit, code designed to take advantage of a bug and disrupt a computer's proper execution. Bugs are usually not the fault of the computer. Since computers merely execute the instructions they are given, bugs are nearly always the result of programmer error or an oversight made in the program's design.


Admiral Grace Hopper, an American computer scientist and developer of the first compiler, is credited for having first used the term "bugs" in computing after a dead moth was found shorting a relay in the Harvard Mark II computer in September 1947.


A general purpose computer has four main components: the arithmetic logic unit (ALU), the control unit, the memory, and the input and output devices (collectively termed I/O). These parts are interconnected by buses, often made of groups of wires.


Inside each of these parts are thousands to trillions of small electrical circuits which can be turned off or on by means of an electronic switch. Each circuit represents a bit (binary digit) of information so that when the circuit is on it represents a "1", and when off it represents a "0" (in positive logic representation). The circuits are arranged in logic gates so that one or more of the circuits may control the state of one or more of the other circuits.


The control unit (often called a control system or central controller) manages the computer's various components; it reads and interprets (decodes) the program instructions, transforming them into control signals that activate other parts of the computer. Control systems in advanced computers may change the order of execution of some instructions to improve performance.


A key component common to all CPUs is the program counter, a special memory cell (a register) that keeps track of which location in memory the next instruction is to be read from.


Since the program counter is (conceptually) just another set of memory cells, it can be changed by calculations done in the ALU. Adding 100 to the program counter would cause the next instruction to be read from a place 100 locations further down the program. Instructions that modify the program counter are often known as "jumps" and allow for loops (instructions that are repeated by the computer) and often conditional instruction execution (both examples of control flow).


The sequence of operations that the control unit goes through to process an instruction is in itself like a short computer program, and indeed, in some more complex CPU designs, there is another yet smaller computer called a microsequencer, which runs a microcode program that causes all of these events to happen.


The control unit, ALU, and registers are collectively known as a central processing unit (CPU). Early CPUs were composed of many separate components but since the mid-1970s CPUs have typically been constructed on a single integrated circuit called a microprocessor.


The set of arithmetic operations that a particular ALU supports may be limited to addition and subtraction, or might include multiplication, division, trigonometry functions such as sine, cosine, etc., and square roots. Some can only operate on whole numbers (integers) whilst others use floating point to represent real numbers, albeit with limited precision. However, any computer that is capable of performing just the simplest operations can be programmed to break down the more complex operations into simple steps that it can perform. Therefore, any computer can be programmed to perform any arithmetic operation—although it will take more time to do so if its ALU does not directly support the operation. An ALU may also compare numbers and return boolean truth values (true or false) depending on whether one is equal to, greater than or less than the other ("is 64 greater than 65?").


Logic operations involve Boolean logic: AND, OR, XOR, and NOT. These can be useful for creating complicated conditional statements and processing boolean logic.


Superscalar computers may contain multiple ALUs, allowing them to process several instructions simultaneously. Graphics processors and computers with SIMD and MIMD features often contain ALUs that can perform arithmetic on vectors and matrices.


A computer's memory can be viewed as a list of cells into which numbers can be placed or read. Each cell has a numbered "address" and can store a single number. The computer can be instructed to "put the number 123 into the cell numbered 1357" or to "add the number that is in cell 1357 to the number that is in cell 2468 and put the answer into cell 1595." The information stored in memory may represent practically anything. Letters, numbers, even computer instructions can be placed into memory with equal ease. Since the CPU does not differentiate between different types of information, it is the software's responsibility to give significance to what the memory sees as nothing but a series of numbers.


In almost all modern computers, each memory cell is set up to store binary numbers in groups of eight bits (called a byte). Each byte is able to represent 256 different numbers (28 = 256); either from 0 to 255 or −128 to +127. To store larger numbers, several consecutive bytes may be used (typically, two, four or eight). When negative numbers are required, they are usually stored in two's complement notation. Other arrangements are possible, but are usually not seen outside of specialized applications or historical contexts. A computer can store any kind of information in memory if it can be represented numerically. Modern computers have billions or even trillions of bytes of memory.


The CPU contains a special set of memory cells called registers that can be read and written to much more rapidly than the main memory area. There are typically between two and one hundred registers depending on the type of CPU. Registers are used for the most frequently needed data items to avoid having to access main memory every time data is needed. As data is constantly being worked on, reducing the need to access main memory (which is often slow compared to the ALU and control units) greatly increases the computer's speed.


RAM can be read and written to anytime the CPU commands it, but ROM is preloaded with data and software that never changes, therefore the CPU can only read from it. ROM is typically used to store the computer's initial start-up instructions. In general, the contents of RAM are erased when the power to the computer is turned off, but ROM retains its data indefinitely. In a PC, the ROM contains a specialized program called the BIOS that orchestrates loading the computer's operating system from the hard disk drive into RAM whenever the computer is turned on or reset. In embedded computers, which frequently do not have disk drives, all of the required software may be stored in ROM. Software stored in ROM is often called firmware, because it is notionally more like hardware than software. Flash memory blurs the distinction between ROM and RAM, as it retains its data when turned off but is also rewritable. It is typically much slower than conventional ROM and RAM however, so its use is restricted to applications where high speed is unnecessary.


In more sophisticated computers there may be one or more RAM cache memories, which are slower than registers but faster than main memory. Generally computers with this sort of cache are designed to move frequently needed data into the cache automatically, often without the need for any intervention on the programmer's part.


I/O is the means by which a computer exchanges information with the outside world. Devices that provide input or output to the computer are called peripherals. On a typical personal computer, peripherals include input devices like the keyboard and mouse, and output devices such as the display and printer. Hard disk drives, floppy disk drives and optical disc drives serve as both input and output devices. Computer networking is another form of I/O.


While a computer may be viewed as running one gigantic program stored in its main memory, in some systems it is necessary to give the appearance of running several programs simultaneously. This is achieved by multitasking i.e. having the computer switch rapidly between running each program in turn.


One means by which this is done is with a special signal called an interrupt, which can periodically cause the computer to stop executing instructions where it was and do something else instead. By remembering where it was executing prior to the interrupt, the computer can return to that task later. If several programs are running "at the same time". then the interrupt generator might be causing several hundred interrupts per second, causing a program switch each time. Since modern computers typically execute instructions several orders of magnitude faster than human perception, it may appear that many programs are running at the same time even though only one is ever executing in any given instant. This method of multitasking is sometimes termed "time-sharing" since each program is allocated a "slice" of time in turn.


Seemingly, multitasking would cause a computer that is switching between several programs to run more slowly, in direct proportion to the number of programs it is running, but most programs spend much of their time waiting for slow input/output devices to complete their tasks. If a program is waiting for the user to click on the mouse or press a key on the keyboard, then it will not take a "time slice" until the event it is waiting for has occurred. This frees up time for other programs to execute so that many programs may be run simultaneously without unacceptable speed loss.


Some computers are designed to distribute their work across several CPUs in a multiprocessing configuration, a technique once employed only in large and powerful machines such as supercomputers, mainframe computers and servers. Multiprocessor and multi-core (multiple CPUs on a single integrated circuit) personal and laptop computers are now widely available, and are being increasingly used in lower-end markets as a result.


Supercomputers in particular often have highly unique architectures that differ significantly from the basic stored-program architecture and from general purpose computers. They often feature thousands of CPUs, customized high-speed interconnects, and specialized computing hardware. Such designs tend to be useful only for specialized tasks due to the large scale of program organization required to successfully utilize most of the available resources at once. Supercomputers usually see usage in large-scale simulation, graphics rendering, and cryptography applications, as well as with other so-called "embarrassingly parallel" tasks.


Computers have been used to coordinate information between multiple locations since the 1950s. The U.S. military's SAGE system was the first large-scale example of such a system, which led to a number of special-purpose commercial systems such as Sabre.


In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. The effort was funded by ARPA (now DARPA), and the computer network that resulted was called the ARPANET. The technologies that made the Arpanet possible spread and evolved.


In time, the network spread beyond academic and military institutions and became known as the Internet. The emergence of networking involved a redefinition of the nature and boundaries of the computer. Computer operating systems and applications were modified to include the ability to define and access the resources of other computers on the network, such as peripheral devices, stored information, and the like, as extensions of the resources of an individual computer. Initially these facilities were available primarily to people working in high-tech environments, but in the 1990s the spread of applications like e-mail and the World Wide Web, combined with the development of cheap, fast networking technologies like Ethernet and ADSL saw computer networking become almost ubiquitous. In fact, the number of computers that are networked is growing phenomenally. A very large proportion of personal computers regularly connect to the Internet to communicate and receive information. "Wireless" networking, often utilizing mobile phone networks, has meant networking is becoming increasingly ubiquitous even in mobile computing environments.


The ability to store and execute lists of instructions called programs makes computers extremely versatile, distinguishing them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a minimum capability (being Turing-complete) is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, any type of computer (netbook, supercomputer, cellular automaton, etc.) is able to perform the same computational tasks, given enough time and storage capacity.


A computer does not need to be electronic, nor even have a processor, nor RAM, nor even a hard disk. While popular usage of the word "computer" is synonymous with a personal electronic computer, the modern definition of a computer is literally: "A device that computes, especially a programmable [usually] electronic machine that performs high-speed mathematical or logical operations or that assembles, stores, correlates, or otherwise processes information." Any device which processes information qualifies as a computer, especially if the processing is purposeful.[citation needed]


Historically, computers evolved from mechanical computers and eventually from vacuum tubes to transistors. However, conceptually computational systems as flexible as a personal computer can be built out of almost anything. For example, a computer can be made out of billiard balls (billiard ball computer); an often quoted example.[citation needed] More realistically, modern computers are made out of transistors made of photolithographed semiconductors.


There is active research to make computers out of many promising new types of technology, such as optical computers, DNA computers, neural computers, and quantum computers. Most computers are universal, and are able to calculate any computable function, and are limited only by their memory capacity and operating speed. However different designs of computers can give very different performance for particular problems; for example quantum computers can potentially break some modern encryption algorithms (by quantum factoring) very quickly.


A computer will solve problems in exactly the way it is programmed to, without regard to efficiency, alternative solutions, possible shortcuts, or possible errors in the code. Computer programs that learn and adapt are part of the emerging field of artificial intelligence and machine learning.


The term hardware covers all of those parts of a computer that are tangible objects. Circuits, displays, power supplies, cables, keyboards, printers and mice are all hardware.


Software refers to parts of the computer which do not have a material form, such as programs, data, protocols, etc. When software is stored in hardware that cannot easily be modified (such as BIOS ROM in an IBM PC compatible), it is sometimes called "firmware".


Firmware is the technology which has the combination of both hardware and software such as BIOS chip inside a computer. This chip (hardware) is located on the motherboard and has the BIOS set up (software) stored in it.


When unprocessed data is sent to the computer with the help of input devices, the data is processed and sent to output devices. The input devices may be hand-operated or automated. The act of processing is mainly regulated by the CPU. Some examples of hand-operated input devices are:


Black people is a term used in certain countries, often in socially based systems of racial classification or of ethnicity, to describe persons who are perceived to be dark-skinned compared to other given populations. As such, the meaning of the expression varies widely both between and within societies, and depends significantly on context. For many other individuals, communities and countries, "black" is also perceived as a derogatory, outdated, reductive or otherwise unrepresentative label, and as a result is neither used nor defined.


Different societies apply differing criteria regarding who is classified as "black", and these social constructs have also changed over time. In a number of countries, societal variables affect classification as much as skin color, and the social criteria for "blackness" vary. For example, in North America the term black people is not necessarily an indicator of skin color or majority ethnic ancestry, but it is instead a socially based racial classification related to being African American, with a family history associated with institutionalized slavery. In South Africa and Latin America, for instance, mixed-race people are generally not classified as "black." In South Pacific regions such as Australia and Melanesia, European colonists applied the term "black" or it was used by populations with different histories and ethnic origin.


The Romans interacted with and later conquered parts of Mauretania, an early state that covered modern Morocco, western Algeria, and the Spanish cities Ceuta and Melilla during the classical period. The people of the region were noted in Classical literature as Mauri, which was subsequently rendered as Moors in English.


Numerous communities of dark-skinned peoples are present in North Africa, some dating from prehistoric communities. Others are descendants of the historical Trans-Saharan trade in peoples and/or, and after the Arab invasions of North Africa in the 7th century, descendants of slaves from the Arab Slave Trade in North Africa.


In the 18th century, the Moroccan Sultan Moulay Ismail "the Bloodthirsty" (1672–1727) raised a corps of 150,000 black slaves, called his Black Guard, who coerced the country into submission.


According to Dr. Carlos Moore, resident scholar at Brazil's University of the State of Bahia, in the 21st century Afro-multiracials in the Arab world, including Arabs in North Africa, self-identify in ways that resemble multi-racials in Latin America. He claims that black-looking Arabs, much like black-looking Latin Americans, consider themselves white because they have some distant white ancestry.


Egyptian President Anwar Sadat had a mother who was a dark-skinned Nubian Sudanese woman and a father who was a lighter-skinned Egyptian. In response to an advertisement for an acting position, as a young man he said, "I am not white but I am not exactly black either. My blackness is tending to reddish".


Due to the patriarchal nature of Arab society, Arab men, including during the slave trade in North Africa, enslaved more black women than men. They used more black female slaves in domestic service and agriculture than males. The men interpreted the Qur'an to permit sexual relations between a male master and his female slave outside of marriage (see Ma malakat aymanukum and sex), leading to many mixed-race children. When an enslaved woman became pregnant with her Arab master's child, she was considered as umm walad or "mother of a child", a status that granted her privileged rights. The child was given rights of inheritance to the father's property, so mixed-race children could share in any wealth of the father. Because the society was patrilineal, the children took their fathers' social status at birth and were born free.


Some succeeded their fathers as rulers, such as Sultan Ahmad al-Mansur, who ruled Morocco from 1578 to 1608. He was not technically considered as a mixed-race child of a slave; his mother was Fulani and a concubine of his father. Such tolerance for black persons, even when technically "free", was not so common in Morocco. The long association of sub-Saharan peoples as slaves is shown in the term abd (Arabic: عبد,) (meaning "slave"); it is still frequently used in the Arabic-speaking world as a term for black people.


In early 1991, non-Arabs of the Zaghawa tribe of Sudan attested that they were victims of an intensifying Arab apartheid campaign, segregating Arabs and non-Arabs (specifically people of sub-Saharan African descent). Sudanese Arabs, who controlled the government, were widely referred to as practicing apartheid against Sudan's non-Arab citizens. The government was accused of "deftly manipulat(ing) Arab solidarity" to carry out policies of apartheid and ethnic cleansing.


American University economist George Ayittey accused the Arab government of Sudan of practicing acts of racism against black citizens. According to Ayittey, "In Sudan... the Arabs monopolized power and excluded blacks – Arab apartheid." Many African commentators joined Ayittey in accusing Sudan of practising Arab apartheid.


Alan Dershowitz described Sudan as an example of a government that "actually deserve(s)" the appellation "apartheid." Former Canadian Minister of Justice Irwin Cotler echoed the accusation.


In South Africa, the period of colonization resulted in many unions and marriages between European men and African women from various tribes, resulting in mixed-race children. As the Europeans acquired territory and imposed rule over the Africans, they generally pushed mixed-race and Africans into second-class status. During the first half of the 20th century, the Afrikaaner-dominated government classified the population according to four main racial groups: Black, White, Asian (mostly Indian), and Coloured. The Coloured group included people of mixed Bantu, Khoisan, and European descent (with some Malay ancestry, especially in the Western Cape). The Coloured definition occupied an intermediary political position between the Black and White definitions in South Africa. It imposed a system of legal racial segregation, a complex of laws known as apartheid.


The apartheid bureaucracy devised complex (and often arbitrary) criteria in the Population Registration Act of 1945 to determine who belonged in which group. Minor officials administered tests to enforce the classifications. When it was unclear from a person's physical appearance whether the individual should be considered Coloured or Black, the "pencil test" was used. A pencil was inserted into a person's hair to determine if the hair was kinky enough to hold the pencil, rather than having it pass through, as it would with smoother hair. If so, the person was classified as Black. Such classifications sometimes divided families.


Sandra Laing is a South African woman who was classified as Coloured by authorities during the apartheid era, due to her skin colour and hair texture, although her parents could prove at least three generations of European ancestors. At age 10, she was expelled from her all-white school. The officials' decisions based on her anomalous appearance disrupted her family and adult life. She was the subject of the 2008 biographical dramatic film Skin, which won numerous awards.


During the apartheid era, those classed as "Coloured" were oppressed and discriminated against. But, they had limited rights and overall had slightly better socioeconomic conditions than those classed as "Black". The government required that Blacks and Coloureds live in areas separate from Whites, creating large townships located away from the cities as areas for Blacks.


In the post-apartheid era, the Constitution of South Africa has declared the country to be a "Non-racial democracy". In an effort to redress past injustices, the ANC government has introduced laws in support of affirmative action policies for Blacks; under these they define "Black" people to include "Africans", "Coloureds" and "Asians". Some affirmative action policies favor "Africans" over "Coloureds" in terms of qualifying for certain benefits. Some South Africans categorized as "African Black" say that "Coloureds" did not suffer as much as they did during apartheid. "Coloured" South Africans are known to discuss their dilemma by saying, "we were not white enough under apartheid, and we are not black enough under the ANC (African National Congress)".[citation needed]


In 2008, the High Court in South Africa ruled that Chinese South Africans who were residents during the apartheid era (and their descendants) are to be reclassified as "Black people," solely for the purposes of accessing affirmative action benefits, because they were also "disadvantaged" by racial discrimination. Chinese people who arrived in the country after the end of apartheid do not qualify for such benefits.


Other than by appearance, "Coloureds" can usually be distinguished from "Blacks" by language. Most speak Afrikaans or English as a first language, as opposed to Bantu languages such as Zulu or Xhosa. They also tend to have more European-sounding names than Bantu names.


Historians estimate that between the advent of Islam in 650CE and the abolition of slavery in the Arabian Peninsula in the mid-20th century, 10 to 18 million sub-Saharan Black Africans were enslaved by Arab slave traders and transported to the Arabian Peninsula and neighboring countries. This number far exceeded the number of slaves who were taken to the Americas. Several factors affected the visibility of descendants of this diaspora in 21st-century Arab societies: The traders shipped more female slaves than males, as there was a demand for them to serve as concubines in harems in the Arabian Peninsula and neighboring countries. Male slaves were castrated in order to serve as harem guards. The death toll of Black African slaves from forced labor was high. The mixed-race children of female slaves and Arab owners were assimilated into the Arab owners' families under the patrilineal kinship system. As a result, few distinctive Afro-Arab black communities have survived in the Arabian Peninsula and neighboring countries.


Genetic studies have found significant African female-mediated gene flow in Arab communities in the Arabian Peninsula and neighboring countries, with an average of 38% of maternal lineages in Yemen are of direct African descent, 16% in Oman-Qatar, and 10% in Saudi Arabia-United Arab Emirates.


Distinctive and self-identified black communities have been reported in countries such as Iraq, with a reported 1.2 million black people, and they attest to a history of discrimination. African-Iraquis have sought minority status from the government, which would reserve some seats in Parliament for representatives of their population. According to Alamin M. Mazrui et al., generally in the Arabian Peninsula and neighboring countries, most of those of visible African descent are still classified and identify as Arab, not black.


About 150,000 East African and black people live in Israel, amounting to just over 2% of the nation's population. The vast majority of these, some 120,000, are Beta Israel, most of whom are recent immigrants who came during the 1980s and 1990s from Ethiopia. In addition, Israel is home to over 5,000 members of the African Hebrew Israelites of Jerusalem movement that are descendants of African Americans who emigrated to Israel in the 20th century, and who reside mainly in a distinct neighborhood in the Negev town of Dimona. Unknown numbers of black converts to Judaism reside in Israel, most of them converts from the United Kingdom, Canada, and the United States.


Additionally, there are around 60,000 non-Jewish African immigrants in Israel, some of whom have sought asylum. Most of the migrants are from communities in Sudan and Eritrea, particularly the Niger-Congo-speaking Nuba groups of the southern Nuba Mountains; some are illegal immigrants.


Beginning several centuries ago, during the period of the Ottoman Empire, tens of thousands of Black Africans were brought by slave traders to plantations and agricultural areas situated between Antalya and Istanbul in present-day Turkey. Some of their descendants remained in situ, and many migrated to larger cities and towns. Other blacks slaves were transported to Crete, from where they or their descendants later reached the İzmir area through the population exchange between Greece and Turkey in 1923, or indirectly from Ayvalık in pursuit of work.


The Siddi are an ethnic group inhabiting India and Pakistan whose members are descended from Bantu peoples from Southeast Africa that were brought to the Indian subcontinent as slaves by Arab and Portuguese merchants. Although it is commonly believed locally that "Siddi" derives from a word meaning "black", the term is actually derived from "Sayyid", the title borne by the captains of the Arab vessels that first brought Siddi settlers to the area. In the Makran strip of the Sindh and Balochistan provinces in southwestern Pakistan, these Bantu descendants are known as the Makrani. There was a brief "Black Power" movement in Sindh in the 1960s and many Siddi are proud of and celebrate their African ancestry.


The Negritos are believed to be the first inhabitants of Southeast Asia. Once inhabiting Taiwan, Vietnam, and various other parts of Asia, they are now confined primarily to Thailand, the Malay Archipelago, and the Andaman and Nicobar Islands. Negrito means "little black people" in Spanish (negrito is the Spanish diminutive of negro, i.e., "little black person"); it is what the Spaniards called the short-statured, hunter-gatherer autochthones that they encountered in the Philippines. Despite this, Negritos are never referred to as black today, and doing so would cause offense. The term Negrito itself has come under criticism in countries like Malaysia, where it is now interchangeable with the more acceptable Semang, although this term actually refers to a specific group. The common Thai word for Negritos literally means "frizzy hair".


The term "Moors" has been used in Europe in a broader, somewhat derogatory sense to refer to Muslims, especially those of Arab or Berber descent, whether living in North Africa or Iberia. Moors were not a distinct or self-defined people. Medieval and early modern Europeans applied the name to Muslim Arabs, Berbers, Black Africans and Europeans alike.


Isidore of Seville, writing in the 7th century, claimed that the Latin word Maurus was derived from the Greek mauron, μαύρον, which is the Greek word for black. Indeed, by the time Isidore of Seville came to write his Etymologies, the word Maurus or "Moor" had become an adjective in Latin, "for the Greeks call black, mauron". "In Isidore’s day, Moors were black by definition…"


Afro-Spaniards are Spanish nationals of West/Central African descent. They today mainly come from Angola, Brazil, Cameroon, Cape Verde, Equatorial Guinea, Ghana, Gambia, Guinea-Bissau, Mali, Nigeria and Senegal. Additionally, many Afro-Spaniards born in Spain are from the former Spanish colony Equatorial Guinea. Today, there are an estimated 683,000 Afro-Spaniards in Spain.


According to the Office for National Statistics, at the 2001 census there were over a million black people in the United Kingdom; 1% of the total population described themselves as "Black Caribbean", 0.8% as "Black African", and 0.2% as "Black other". Britain encouraged the immigration of workers from the Caribbean after World War II; the first symbolic movement was those who came on the ship the Empire Windrush. The preferred official umbrella term is "black and minority ethnic" (BME), but sometimes the term "black" is used on its own, to express unified opposition to racism, as in the Southall Black Sisters, which started with a mainly British Asian constituency, and the National Black Police Association, which has a membership of "African, African-Caribbean and Asian origin".


As African states became independent in the 1960s, the Soviet Union offered many of their citizens the chance to study in Russia. Over a period of 40 years, about 400,000 African students from various countries moved to Russia to pursue higher studies, including many Black Africans. This extended beyond the Soviet Union to many countries of the Eastern bloc.


Due to the Ottoman slave trade that had flourished in the Balkans, the coastal town of Ulcinj in Montenegro had its own black community. As a consequence of the slave trade and privateer activity, it is told how until 1878 in Ulcinj 100 black people lived. The Ottoman Army also deployed an estimated 30,000 Black African troops and cavalrymen to its expedition in Hungary during the Austro-Turkish War of 1716–18.


Indigenous Australians have been referred to as "black people" in Australia since the early days of European settlement. While originally related to skin colour, the term is used to today to indicate Aboriginal or Torres Strait Islander ancestry in general and can refer to people of any skin pigmentation.


Being identified as either "black" or "white" in Australia during the 19th and early 20th centuries was critical in one's employment and social prospects. Various state-based Aboriginal Protection Boards were established which had virtually complete control over the lives of Indigenous Australians – where they lived, their employment, marriage, education and included the power to separate children from their parents. Aborigines were not allowed to vote and were often confined to reserves and forced into low paid or effectively slave labour. The social position of mixed-race or "half-caste" individuals varied over time. A 1913 report by Sir Baldwin Spencer states that:


After the First World War, however, it became apparent that the number of mixed-race people was growing at a faster rate than the white population, and by 1930 fear of the "half-caste menace" undermining the White Australia ideal from within was being taken as a serious concern. Dr. Cecil Cook, the Northern Territory Protector of Natives, noted that:


The official policy became one of biological and cultural assimilation: "Eliminate the full-blood and permit the white admixture to half-castes and eventually the race will become white". This led to different treatment for "black" and "half-caste" individuals, with lighter-skinned individuals targeted for removal from their families to be raised as "white" people, restricted from speaking their native language and practising traditional customs, a process now known as the Stolen Generation.


The second half of the 20th century to the present has seen a gradual shift towards improved human rights for Aboriginal people. In a 1967 referendum over 90% of the Australian population voted to end constitutional discrimination and to include Aborigines in the national census. During this period many Aboriginal activists began to embrace the term "black" and use their ancestry as a source of pride. Activist Bob Maza said:


In 1978 Aboriginal writer Kevin Gilbert received the National Book Council award for his book Living Black: Blacks Talk to Kevin Gilbert, a collection of Aboriginal people's stories, and in 1998 was awarded (but refused to accept) the Human Rights Award for Literature for Inside Black Australia, a poetry anthology and exhibition of Aboriginal photography. In contrast to previous definitions based solely on the degree of Aboriginal ancestry, in 1990 the Government changed the legal definition of Aboriginal to include any:


This nationwide acceptance and recognition of Aboriginal people led to a significant increase in the number of people self-identifying as Aboriginal or Torres Strait Islander. The reappropriation of the term "black" with a positive and more inclusive meaning has resulted in its widespread use in mainstream Australian culture, including public media outlets, government agencies, and private companies. In 2012, a number of high-profile cases highlighted the legal and community attitude that identifying as Aboriginal or Torres Strait Islander is not dependent on skin colour, with a well-known boxer Anthony Mundine being widely criticised for questioning the "blackness" of another boxer and journalist Andrew Bolt being successfully sued for publishing discriminatory comments about Aboriginals with light skin.


In the Colonial America of 1619, John Rolfe used negars in describing the slaves who were captured from West Africa and then shipped to the Virginia colony. Later American English spellings, neger and neggar, prevailed in a northern colony, New York under the Dutch, and in metropolitan Philadelphia's Moravian and Pennsylvania Dutch communities; the African Burial Ground in New York City originally was known by the Dutch name "Begraafplaats van de Neger" (Cemetery of the Negro); an early US occurrence of neger in Rhode Island, dates from 1625. Thomas Jefferson also used the term "black" in his Notes on the State of Virginia in allusion to the slave populations.


By the 1900s, nigger had become a pejorative word in the United States. In its stead, the term colored became the mainstream alternative to negro and its derived terms. After the African-American Civil rights movement, the terms colored and negro gave way to "black". Negro had superseded colored as the most polite word for African Americans at a time when black was considered more offensive. This term was accepted as normal, including by people classified as Negroes, until the later Civil Rights movement in the late 1960s. One well-known example is the identification by Reverend Martin Luther King, Jr. of his own race as "Negro" in his famous speech of 1963, I Have a Dream. During the American Civil Rights movement of the 1950s and 1960s, some African-American leaders in the United States, notably Malcolm X, objected to the word Negro because they associated it with the long history of slavery, segregation, and discrimination that treated African Americans as second-class citizens, or worse. Malcolm X preferred Black to Negro, but later gradually abandoned that as well for Afro-American after leaving the Nation of Islam.


In the first 200 years that black people were in the United States, they primarily identified themselves by their specific ethnic group (closely allied to language) and not by skin color. Individuals identified themselves, for example, as Ashanti, Igbo, Bakongo, or Wolof. However, when the first captives were brought to the Americas, they were often combined with other groups from West Africa, and individual ethnic affiliations were not generally acknowledged by English colonists. In areas of the Upper South, different ethnic groups were brought together. This is significant as the captives came from a vast geographic region: the West African coastline stretching from Senegal to Angola and in some cases from the south-east coast such as Mozambique. A new African-American identity and culture was born that incorporated elements of the various ethnic groups and of European cultural heritage, resulting in fusions such as the Black church and Black English. This new identity was based on provenance and slave status rather than membership in any one ethnic group.[citation needed] By contrast, slave records from Louisiana show that the French and Spanish colonists recorded more complete identities of the West Africans, including ethnicities and given tribal names.


The US racial or ethnic classification "black" refers to people with all possible kinds of skin pigmentation, from the darkest through to the very lightest skin colors, including albinos, if they are believed by others to have West African ancestry (in any discernible percentage), or to exhibit cultural traits associated with being "African American". As a result, in the United States the term "black people" is not an indicator of skin color or ethnic origin but is instead a socially based racial classification related to being African American, with a family history associated with institutionalized slavery. Relatively dark-skinned people can be classified as white if they fulfill other social criteria of "whiteness", and relatively light-skinned people can be classified as black if they fulfill the social criteria for "blackness" in a particular setting.


By that time, the majority of black people in the United States were native-born, so the use of the term "African" became problematic. Though initially a source of pride, many blacks feared that the use of African as an identity would be a hindrance to their fight for full citizenship in the US. They also felt that it would give ammunition to those who were advocating repatriating black people back to Africa. In 1835, black leaders called upon Black Americans to remove the title of "African" from their institutions and replace it with "Negro" or "Colored American". A few institutions chose to keep their historic names, such as the African Methodist Episcopal Church. African Americans popularly used the terms "Negro" or "colored" for themselves until the late 1960s.


In 1988, the civil rights leader Jesse Jackson urged Americans to use instead the term "African American" because it had a historical cultural base and was a construction similar to terms used by European descendants, such as German American, Italian American, etc. Since then, African American and black have often had parallel status. However, controversy continues over which if any of the two terms is more appropriate. Maulana Karenga argues that the term African-American is more appropriate because it accurately articulates their geographical and historical origin.[citation needed] Others have argued that "black" is a better term because "African" suggests foreignness, although Black Americans helped found the United States. Still others believe that the term black is inaccurate because African Americans have a variety of skin tones. Some surveys suggest that the majority of Black Americans have no preference for "African American" or "Black", although they have a slight preference for "black" in personal settings and "African American" in more formal settings.


The U.S. census race definitions says a "black" is a person having origins in any of the black (sub-Saharan) racial groups of Africa. It includes people who indicate their race as "Black, African Am., or Negro" or who provide written entries such as African American, Afro-American, Kenyan, Nigerian, or Haitian. The Census Bureau notes that these classifications are socio-political constructs and should not be interpreted as scientific or anthropological. Most African Americans also have European ancestry in varying amounts; a lesser proportion have some Native American ancestry. For instance, genetic studies of African Americans show an ancestry that is on average 17–18% European.


From the late 19th century, the South used a colloquial term, the one-drop rule, to classify as black a person of any known African ancestry. This practice of hypodescent was not put into law until the early 20th century. Legally the definition varied from state to state. Racial definition was more flexible in the 18th and 19th centuries before the American Civil War. For instance, President Thomas Jefferson held persons who were legally white (less than 25% black) according to Virginia law at the time, but, because they were born to slave mothers, they were born into slavery, according to the principle of partus sequitur ventrem, which Virginia adopted into law in 1662.


The concept of blackness in the United States has been described as the degree to which one associates themselves with mainstream African-American culture, politics, and values. To a certain extent, this concept is not so much about race but more about political orientation, culture and behavior. Blackness can be contrasted with "acting white", where black Americans are said to behave with assumed characteristics of stereotypical white Americans with regard to fashion, dialect, taste in music, and possibly, from the perspective of a significant number of black youth, academic achievement.


Due to the often political and cultural contours of blackness in the United States, the notion of blackness can also be extended to non-black people. Toni Morrison once described Bill Clinton as the first black President of the United States, because, as she put it, he displayed "almost every trope of blackness". Christopher Hitchens was offended by the notion of Clinton as the first black president, noting, "Mr Clinton, according to Toni Morrison, the Nobel Prize-winning novelist, is our first black President, the first to come from the broken home, the alcoholic mother, the under-the-bridge shadows of our ranking systems. Thus, we may have lost the mystical power to divine diabolism, but we can still divine blackness by the following symptoms: broken homes, alcoholic mothers, under-the-bridge habits and (presumable from the rest of [Arthur] Miller's senescent musings) the tendency to sexual predation and to shameless perjury about same." Some black activists were also offended, claiming that Clinton used his knowledge of black culture to exploit black people for political gain as no other president had before, while not serving black interests. They cite the lack of action during the Rwandan Genocide and his welfare reform, which Larry Roberts said had led to the worst child poverty since the 1960s. Others cited that the number of black people in jail increased during his administration.


In July 2012, Ancestry.com reported on historic and DNA research by its staff that discovered that Obama is likely a descendant through his mother of John Punch, considered by some historians to be the first African slave in the Virginia colony. An indentured servant, he was "bound for life" in 1640 after trying to escape. The story of him and his descendants is that of multi-racial America since it appeared he and his sons married or had unions with white women, likely indentured servants and working-class like them. Their multi-racial children were free because they were born to free English women. Over time, Obama's line of the Bunch family (as they became known) were property owners and continued to "marry white"; they became part of white society, likely by the early to mid-18th century.


Approximately 12 million Africans were shipped to the Americas during the Atlantic slave trade from 1492 to 1888, with 11.5 million of those shipped to South America and the Caribbean. Brazil was the largest importer in the Americas, with 5.5 million African slaves imported, followed by the British Caribbean with 2.76 million, the Spanish Caribbean and Spanish Mainland with 1.59 million Africans, and the French Caribbean with 1.32 million. Today their descendants number approximately 150 million in South America and the Caribbean. In addition to skin color, other physical characteristics such as facial features and hair texture are often variously used in classifying peoples as black in South America and the Caribbean. In South America and the Caribbean, classification as black is also closely tied to social status and socioeconomic variables, especially in light of social conceptions of "blanqueamiento" (racial whitening) and related concepts.


The concept of race in Brazil is complex. A Brazilian child was never automatically identified with the racial type of one or both of his or her parents, nor were there only two categories to choose from. Between an individual of unmixed West African descent and a very light mulatto individual, more than a dozen racial categories were acknowledged, based on various combinations of hair color, hair texture, eye color, and skin color. These types grade into each other like the colors of the spectrum, and no one category stands significantly isolated from the rest. In Brazil, people are classified by appearance, not heredity.


Scholars disagree over the effects of social status on racial classifications in Brazil. It is generally believed that achieving upward mobility and education results in individuals being classified as a category of lighter skin. The popular claim is that in Brazil, poor whites are considered black and wealthy blacks are considered white. Some scholars disagree, arguing that "whitening" of one's social status may be open to people of mixed race, a large part of the population known as pardo, but a person perceived as preto (black) will continue to be classified as black regardless of wealth or social status.


From the years 1500 to 1850, an estimated 3.5 million captives were forcibly shipped from West/Central Africa to Brazil; the territory received the highest number of slaves of any country in the Americas. Scholars estimate that more than half of the Brazilian population is at least in part descended from these individuals. Brazil has the largest population of Afro-descendants outside of Africa. In contrast to the US, during the slavery period and after, the Portuguese colonial government and later Brazilian government did not pass formal anti-miscegenation or segregation laws. As in other Latin countries, intermarriage was prevalent during the colonial period and continued afterward. In addition, people of mixed race (pardo) often tended to marry white, and their descendants became accepted as white. As a result, some of the European descended population also has West African or Amerindian blood. According to the last census of the 20th century, in which Brazilians could choose from five color/ethnic categories with which they identified, 54% of individuals identified as white, 6.2% identified as black, and 39.5% identified as pardo (brown) — a broad multi-racial category, including tri-racial persons.


By the 2000 census, demographic changes including the end to slavery, immigration from Europe and Asia, assimilation of multiracial persons, and other factors resulted in a population in which 6.2% of the population identified as black, 40% as pardo, and 55% as white. Essentially most of the black population was absorbed into the multi-racial category by intermixing. A 2007 genetic study found that at least 29% of the middle-class, white Brazilian population had some recent (since 1822 and the end of the colonial period) African ancestry.


Because of the acceptance of miscegenation, Brazil has avoided the binary polarization of society into black and white. In addition, it abolished slavery without a civil war. The bitter and sometimes violent racial tensions that have divided the US are notably absent in Brazil. According to the 2010 census, 6.7% of Brazilians said they were black, compared with 6.2% in 2000, and 43.1% said they were racially mixed, up from 38.5%. In 2010, Elio Ferreira de Araujo, Brazil's minister for racial equality, attributed the increases to growing pride among his country's black and indigenous communities.


In the US, African Americans, who include multiracial people, earn 75% of what white people earn. In Brazil, people of color earn less than 50% of what whites earn. Some have posited that the facts of lower socioeconomic status for people of color suggest that Brazil practices a kind of one-drop rule, or discrimination against people who are not visibly European in ancestry. The gap in income between blacks and other non-whites is relatively small compared to the large gap between whites and all people of color. Other social factors, such as illiteracy and education levels, show the same patterns of disadvantage for people of color. Some commentators observe that the United States practice of segregation and white supremacy in the South, and discrimination in many areas outside that region, forced many African Americans to unite in the civil rights struggle. They suggest that the fluid nature of race in Brazil has divided individuals of African descent, between those with more or less ancestry. As a result, they have not united for a stronger civil rights movement.[citation needed]


Though Brazilians of at least partial African heritage make up a large percentage of the population, few blacks have been elected as politicians. The city of Salvador, Bahia, for instance, is 80% people of color, but voters have not elected a mayor of color. Journalists like to say that US cities with black majorities, such as Detroit and New Orleans, have not elected white mayors since after the civil rights movement, when the Voting Rights Act of 1965 protected the franchise for minorities, and blacks in the South regained the power to vote for the first time since the turn of the 20th century. New Orleans elected its first black mayor in the 1970s. New Orleans elected a white mayor after the widescale disruption and damage of Hurricane Katrina in 2005.


Critics note that people of color have limited media visibility. The Brazilian media has been accused of hiding or overlooking the nation's Black, Indigenous, Multiracial and East Asian populations. For example, the telenovelas or soaps are criticized for featuring actors who resemble northern Europeans rather than actors of the more prevalent Southern European features) and light-skinned mulatto and mestizo appearance. (Pardos may achieve "white" status if they have attained the middle-class or higher social status).


These patterns of discrimination against non-whites have led some academic and other activists to advocate for use of the Portuguese term negro to encompass all African-descended people, in order to stimulate a "black" consciousness and identity. This proposal has been criticized since the term pardo is considered to include a wide range of multiracial people, such as caboclos (mestizos), assimilated Amerindians and tri-racials, not only people of partial African and European descent. Trying to identify this entire group as "black" would be a false imposition of a different identity from outside the culture and deny people their other, equally valid, ancestries and cultures. It seems a one-drop rule in reverse.


The Times is a British daily national newspaper based in London. It began in 1785 under the title The Daily Universal Register and became The Times on 1 January 1788. The Times and its sister paper The Sunday Times (founded in 1821) are published by Times Newspapers, since 1981 a subsidiary of News UK, itself wholly owned by the News Corp group headed by Rupert Murdoch. The Times and The Sunday Times do not share editorial staff, were founded independently and have only had common ownership since 1967.


The Times is the first newspaper to have borne that name, lending it to numerous other papers around the world, including The Times of India (founded in 1838), The Straits Times (Singapore) (1845), The New York Times (1851), The Irish Times (1859), Le Temps (France) (1861-1942), the Cape Times (South Africa) (1872), the Los Angeles Times (1881), The Seattle Times (1891), The Manila Times (1898), The Daily Times (Malawi) (1900), El Tiempo (Colombia) (1911), The Canberra Times (1926), and The Times (Malta) (1935). In these countries, the newspaper is often referred to as The London Times or The Times of London.


The Times is the originator of the widely used Times Roman typeface, originally developed by Stanley Morison of The Times in collaboration with the Monotype Corporation for its legibility in low-tech printing. In November 2006 The Times began printing headlines in a new font, Times Modern. The Times was printed in broadsheet format for 219 years, but switched to compact size in 2004 in an attempt to appeal more to younger readers and commuters using public transport. The Sunday Times remains a broadsheet.


Though traditionally a moderate newspaper and sometimes a supporter of the Conservative Party, it supported the Labour Party in the 2001 and 2005 general elections. In 2004, according to MORI, the voting intentions of its readership were 40% for the Conservative Party, 29% for the Liberal Democrats, and 26% for Labour. The Times had an average daily circulation of 394,448 in March 2014; in the same period, The Sunday Times had an average daily circulation of 839,077. An American edition of The Times has been published since 6 June 2006. It has been heavily used by scholars and researchers because of its widespread availability in libraries and its detailed index. A complete historical file of the digitized paper is online from Gage Cengage publisher.


The Times was founded by publisher John Walter on 1 January 1785 as The Daily Universal Register, with Walter in the role of editor. Walter had lost his job by the end of 1784 after the insurance company where he was working went bankrupt because of the complaints of a Jamaican hurricane. Being unemployed, Walter decided to set a new business up. It was in that time when Henry Johnson invented the logography, a new typography that was faster and more precise (three years later, it was proved that it was not as efficient as had been said). Walter bought the logography's patent and to use it, he decided to open a printing house, where he would daily produce an advertising sheet. The first publication of the newspaper The Daily Universal Register in Great Britain was 1 January 1785. Unhappy because people always omitted the word Universal, Ellias changed the title after 940 editions on 1 January 1788 to The Times. In 1803, Walter handed ownership and editorship to his son of the same name. Walter Sr had spent sixteen months in Newgate Prison for libel printed in The Times, but his pioneering efforts to obtain Continental news, especially from France, helped build the paper's reputation among policy makers and financiers.


The Times used contributions from significant figures in the fields of politics, science, literature, and the arts to build its reputation. For much of its early life, the profits of The Times were very large and the competition minimal, so it could pay far better than its rivals for information or writers. Beginning in 1814, the paper was printed on the new steam-driven cylinder press developed by Friedrich Koenig. In 1815, The Times had a circulation of 5,000.


Thomas Barnes was appointed general editor in 1817. In the same year, the paper's printer James Lawson, died and passed the business onto his son John Joseph Lawson(1802–1852). Under the editorship of Barnes and his successor in 1841, John Thadeus Delane, the influence of The Times rose to great heights, especially in politics and amongst the City of London. Peter Fraser and Edward Sterling were two noted journalists, and gained for The Times the pompous/satirical nickname 'The Thunderer' (from "We thundered out the other day an article on social and political reform."). The increased circulation and influence of the paper was based in part to its early adoption of the steam-driven rotary printing press. Distribution via steam trains to rapidly growing concentrations of urban populations helped ensure the profitability of the paper and its growing influence.


The Times was the first newspaper to send war correspondents to cover particular conflicts. W. H. Russell, the paper's correspondent with the army in the Crimean War, was immensely influential with his dispatches back to England.


In other events of the nineteenth century, The Times opposed the repeal of the Corn Laws until the number of demonstrations convinced the editorial board otherwise, and only reluctantly supported aid to victims of the Irish Potato Famine. It enthusiastically supported the Great Reform Bill of 1832, which reduced corruption and increased the electorate from 400,000 people to 800,000 people (still a small minority of the population). During the American Civil War, The Times represented the view of the wealthy classes, favouring the secessionists, but it was not a supporter of slavery.


The third John Walter, the founder's grandson, succeeded his father in 1847. The paper continued as more or less independent, but from the 1850s The Times was beginning to suffer from the rise in competition from the penny press, notably The Daily Telegraph and The Morning Post.


During the 19th century, it was not infrequent for the Foreign Office to approach The Times and ask for continental intelligence, which was often superior to that conveyed by official sources.[citation needed]


The Times faced financial extinction in 1890 under Arthur Fraser Walter, but it was rescued by an energetic editor, Charles Frederic Moberly Bell. During his tenure (1890–1911), The Times became associated with selling the Encyclopædia Britannica using aggressive American marketing methods introduced by Horace Everett Hooper and his advertising executive, Henry Haxton. Due to legal fights between the Britannica's two owners, Hooper and Walter Montgomery Jackson, The Times severed its connection in 1908 and was bought by pioneering newspaper magnate, Alfred Harmsworth, later Lord Northcliffe.