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Black

Black is a color that results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white have often been used to describe opposites such as good and evil, the Dark Ages versus Age of Enlightenment, and night versus day. Since the Middle Ages, black has been the symbolic color of solemnity and authority, and for this reason it is still commonly worn by judges and magistrates.

Black was one of the first colors used by artists in Neolithic cave paintings. It was used in ancient Egypt and Greece as the color of the underworld. In the Roman Empire, it became the color of mourning, and over the centuries it was frequently associated with death, evil, witches, and magic. In the 14th century, it was worn by royalty, clergy, judges, and government officials in much of Europe. It became the color worn by English romantic poets, businessmen and statesmen in the 19th century, and a high fashion color in the 20th century. According to surveys in Europe and North America, it is the color most commonly associated with mourning, the end, secrets, magic, force, violence, fear, evil, and elegance.

Black is the most common ink color used for printing books, newspapers and documents, as it provides the highest contrast with white paper and thus is the easiest color to read. Similarly, black text on a white screen is the most common format used on computer screens. the darkest material is made by MIT engineers from vertically aligned carbon nanotubes.

Etymology
The word black comes from Old English blæc ("black, dark", also, "ink"), from Proto-Germanic *blakkaz ("burned"), from Proto-Indo-European *bhleg- ("to burn, gleam, shine, flash"), from base *bhel- ("to shine"), related to Old Saxon blak ("ink"), Old High German blach ("black"), Old Norse blakkr ("dark"), Dutch blaken ("to burn"), and Swedish bläck ("ink"). More distant cognates include Latin flagrare ("to blaze, glow, burn"), and Ancient Greek phlegein ("to burn, scorch"). The Ancient Greeks sometimes used the same word to name different colors, if they had the same intensity. Kuanos' could mean both dark blue and black. The Ancient Romans had two words for black: ater was a flat, dull black, while niger was a brilliant, saturated black. Ater has vanished from the vocabulary, but niger was the source of the country name Nigeria, the English word Negro, and the word for "black" in most modern Romance languages (French: noir; Spanish and Portuguese: negro; Italian: nero; Romanian: negru).

Old High German also had two words for black: swartz for dull black and blach for a luminous black. These are parallelled in Middle English by the terms swart for dull black and blaek for luminous black. Swart still survives as the word swarthy, while blaek became the modern English black. The former is cognate with the words used for black in most modern Germanic languages aside from English (German: schwarz, Dutch: zwart, Swedish: svart, Danish: sort, Icelandic: svartr). In heraldry, the word used for the black color is sable, named for the black fur of the sable, an animal.

Prehistoric
Black was one of the first colors used in art. The Lascaux Cave in France contains drawings of bulls and other animals drawn by paleolithic artists between 18,000 and 17,000 years ago. They began by using charcoal, and later achieved darker pigments by burning bones or grinding a powder of manganese oxide.

Ancient
For the ancient Egyptians, black had positive associations; being the color of fertility and the rich black soil flooded by the Nile. It was the color of Anubis, the god of the underworld, who took the form of a black jackal, and offered protection against evil to the dead. To ancient Greeks, black represented the underworld, separated from the living by the river Acheron, whose water ran black. Those who had committed the worst sins were sent to Tartarus, the deepest and darkest level. In the center was the palace of Hades, the king of the underworld, where he was seated upon a black ebony throne. Black was one of the most important colors used by ancient Greek artists. In the 6th century BC, they began making black-figure pottery and later red figure pottery, using a highly original technique. In black-figure pottery, the artist would paint figures with a glossy clay slip on a red clay pot. When the pot was fired, the figures painted with the slip would turn black, against a red background. Later they reversed the process, painting the spaces between the figures with slip. This created magnificent red figures against a glossy black background.

In the social hierarchy of ancient Rome, purple was reserved for the emperor; red was the color worn by soldiers (red cloaks for the officers, red tunics for the soldiers); white the color worn by the priests, and black was worn by craftsmen and artisans. The black they wore was not deep and rich; the vegetable dyes used to make black were not solid or lasting, so the blacks often faded to gray or brown.

In Latin, the word for black, ater and to darken, atere, were associated with cruelty, brutality and evil. They were the root of the English words "atrocious" and "atrocity". For the Romans, black symbolized death and mourning. In the 2nd century BC Roman magistrates wore a dark toga, called a toga pulla, to funeral ceremonies. Later, under the Empire, the family of the deceased also wore dark colors for a long period; then, after a banquet to mark the end of mourning, exchanged the black for a white toga. In Roman poetry, death was called the hora nigra, the black hour.

The German and Scandinavian peoples worshipped their own goddess of the night, Nótt, who crossed the sky in a chariot drawn by a black horse. They also feared Hel, the goddess of the kingdom of the dead, whose skin was black on one side and red on the other. They also held sacred the raven. They believed that Odin, the king of the Nordic pantheon, had two black ravens, Huginn and Muninn, who served as his agents, traveling the world for him, watching and listening.

Postclassical
In the early Middle Ages, black was commonly associated with darkness and evil. In Medieval paintings, the devil was usually depicted as having human form, but with wings and black skin or hair.

12th and 13th centuries
In fashion, black did not have the prestige of red, the color of the nobility. It was worn by Benedictine monks as a sign of humility and penitence. In the 12th century a famous theological dispute broke out between the Cistercian monks, who wore white, and the Benedictines, who wore black. A Benedictine abbot, Pierre the Venerable, accused the Cistercians of excessive pride in wearing white instead of black. Saint Bernard of Clairvaux, the founder of the Cistercians responded that black was the color of the devil, hell, "of death and sin", while white represented "purity, innocence and all the virtues".

Black symbolized both power and secrecy in the medieval world. The emblem of the Holy Roman Empire of Germany was a black eagle. The black knight in the poetry of the Middle Ages was an enigmatic figure, hiding his identity, usually wrapped in secrecy.

Black ink, invented in China, was traditionally used in the Middle Ages for writing, for the simple reason that black was the darkest color and therefore provided the greatest contrast with white paper or parchment, making it the easiest color to read. It became even more important in the 15th century, with the invention of printing. A new kind of ink, printer's ink, was created out of soot, turpentine and walnut oil. The new ink made it possible to spread ideas to a mass audience through printed books, and to popularize art through black and white prints. Because of its contrast and clarity, black ink on white paper continued to be the standard for printing books, newspapers and documents; and for the same reason black text on a white background is the most common format used on computer screens.

14th and 15th centuries
In the early Middle Ages, princes, nobles and the wealthy usually wore bright colors, particularly scarlet cloaks from Italy. Black was rarely part of the wardrobe of a noble family. The one exception was the fur of the sable. This glossy black fur, from an animal of the marten family, was the finest and most expensive fur in Europe. It was imported from Russia and Poland and used to trim the robes and gowns of royalty.

In the 14th century, the status of black began to change. First, high-quality black dyes began to arrive on the market, allowing garments of a deep, rich black. Magistrates and government officials began to wear black robes, as a sign of the importance and seriousness of their positions. A third reason was the passage of sumptuary laws in some parts of Europe which prohibited the wearing of costly clothes and certain colors by anyone except members of the nobility. The famous bright scarlet cloaks from Venice and the peacock blue fabrics from Florence were restricted to the nobility. The wealthy bankers and merchants of northern Italy responded by changing to black robes and gowns, made with the most expensive fabrics.

The change to the more austere but elegant black was quickly picked up by the kings and nobility. It began in northern Italy, where the Duke of Milan and the Count of Savoy and the rulers of Mantua, Ferrara, Rimini and Urbino began to dress in black. It then spread to France, led by Louis I, Duke of Orleans, younger brother of King Charles VI of France. It moved to England at the end of the reign of King Richard II (1377–1399), where all the court began to wear black. In 1419–20, black became the color of the powerful Duke of Burgundy, Philip the Good. It moved to Spain, where it became the color of the Spanish Habsburgs, of Charles V and of his son, Philip II of Spain (1527–1598). European rulers saw it as the color of power, dignity, humility and temperance. By the end of the 16th century, it was the color worn by almost all the monarchs of Europe and their courts.

16th and 17th centuries
While black was the color worn by the Catholic rulers of Europe, it was also the emblematic color of the Protestant Reformation in Europe and the Puritans in England and America. John Calvin, Philip Melanchthon and other Protestant theologians denounced the richly colored and decorated interiors of Roman Catholic churches. They saw the color red, worn by the pope and his cardinals, as the color of luxury, sin, and human folly. In some northern European cities, mobs attacked churches and cathedrals, smashed the stained glass windows and defaced the statues and decoration. In Protestant doctrine, clothing was required to be sober, simple and discreet. Bright colors were banished and replaced by blacks, browns and grays; women and children were recommended to wear white.

In the Protestant Netherlands, Rembrandt used this sober new palette of blacks and browns to create portraits whose faces emerged from the shadows expressing the deepest human emotions. The Catholic painters of the Counter-Reformation, like Rubens, went in the opposite direction; they filled their paintings with bright and rich colors. The new Baroque churches of the Counter-Reformation were usually shining white inside and filled with statues, frescoes, marble, gold and colorful paintings, to appeal to the public. But European Catholics of all classes, like Protestants, eventually adopted a sober wardrobe that was mostly black, brown and gray.

In the second part of the 17th century, Europe and America experienced an epidemic of fear of witchcraft. People widely believed that the devil appeared at midnight in a ceremony called a Black Mass or black sabbath, usually in the form of a black animal, often a goat, a dog, a wolf, a bear, a deer or a rooster, accompanied by their familiar spirits, black cats, serpents and other black creatures. This was the origin of the widespread superstition about black cats and other black animals. In medieval Flanders, in a ceremony called Kattenstoet, black cats were thrown from the belfry of the Cloth Hall of Ypres to ward off witchcraft.

Witch trials were common in both Europe and America during this period. During the notorious Salem witch trials in New England in 1692–93, one of those on trial was accused of being able turn into a "black thing with a blue cap," and others of having familiars in the form of a black dog, a black cat and a black bird. Nineteen women and men were hanged as witches.

18th and 19th centuries
In the 18th century, during the European Age of Enlightenment, black receded as a fashion color. Paris became the fashion capital, and pastels, blues, greens, yellow and white became the colors of the nobility and upper classes. But after the French Revolution, black again became the dominant color. Black was the color of the industrial revolution, largely fueled by coal, and later by oil. Thanks to coal smoke, the buildings of the large cities of Europe and America gradually turned black. By 1846 the industrial area of the West Midlands of England was "commonly called 'the Black Country'". Charles Dickens and other writers described the dark streets and smoky skies of London, and they were vividly illustrated in the wood-engravings of French artist Gustave Doré.

A different kind of black was an important part of the romantic movement in literature. Black was the color of melancholy, the dominant theme of romanticism. The novels of the period were filled with castles, ruins, dungeons, storms, and meetings at midnight. The leading poets of the movement were usually portrayed dressed in black, usually with a white shirt and open collar, and a scarf carelessly over their shoulder, Percy Bysshe Shelley and Lord Byron helped create the enduring stereotype of the romantic poet.

The invention of inexpensive synthetic black dyes and the industrialization of the textile industry meant that high-quality black clothes were available for the first time to the general population. In the 19th century black gradually became the most popular color of business dress of the upper and middle classes in England, the Continent, and America. Black dominated literature and fashion in the 19th century, and played a large role in painting. James McNeill Whistler made the color the subject of his most famous painting, Arrangement in grey and black number one (1871), better known as Whistler's Mother.

Some 19th-century French painters had a low opinion of black: "Reject black," Paul Gauguin said, "and that mix of black and white they call gray. Nothing is black, nothing is gray." But Édouard Manet used blacks for their strength and dramatic effect. Manet's portrait of painter Berthe Morisot was a study in black which perfectly captured her spirit of independence. The black gave the painting power and immediacy; he even changed her eyes, which were green, to black to strengthen the effect. Henri Matisse quoted the French impressionist Pissarro telling him, "Manet is stronger than us all – he made light with black."

Pierre-Auguste Renoir used luminous blacks, especially in his portraits. When someone told him that black was not a color, Renoir replied: "What makes you think that? Black is the queen of colors. I always detested Prussian blue. I tried to replace black with a mixture of red and blue, I tried using cobalt blue or ultramarine, but I always came back to ivory black."

Vincent van Gogh used black lines to outline many of the objects in his paintings, such as the bed in the famous painting of his bedroom. making them stand apart. His painting of black crows over a cornfield, painted shortly before he died, was particularly agitated and haunting. In the late 19th century, black also became the color of anarchism. (See the section political movements.)

20th and 21st centuries
In the 20th century, black was utilised by Italian and German fascism. (See the section political movements). In art, the colour regained some of the territory that it had lost during the 19th century. The Russian painter Kasimir Malevich, a member of the Suprematist movement, created the Black Square in 1915, is widely considered the first purely abstract painting. He wrote, "The painted work is no longer simply the imitation of reality, but is this very reality ... It is not a demonstration of ability, but the materialization of an idea."

Black was appreciated by Henri Matisse. "When I didn't know what color to put down, I put down black," he said in 1945. "Black is a force: I used black as ballast to simplify the construction ... Since the impressionists it seems to have made continuous progress, taking a more and more important part in color orchestration, comparable to that of the double bass as a solo instrument."

In the 1950s, black came to be a symbol of individuality and intellectual and social rebellion, the color of those who did not accept established norms and values. In Paris, it was worn by Left-Bank intellectuals and performers such as Juliette Gréco, and by some members of the Beat Movement in New York and San Francisco. Black leather jackets were worn by motorcycle gangs such as the Hells Angels and street gangs on the fringes of society in the United States. Black as a color of rebellion was celebrated in such films as The Wild One, with Marlon Brando. By the end of the 20th century, black was the emblematic color of the punk subculture punk fashion, and the goth subculture. Goth fashion, which emerged in England in the 1980s, was inspired by Victorian era mourning dress.

In men's fashion, black gradually ceded its dominance to navy blue, particularly in business suits. Black evening dress and formal dress in general were worn less and less. In 1960, John F. Kennedy was the last American President to be inaugurated wearing formal dress; Lyndon Johnson and his successors were inaugurated wearing business suits.

Women's fashion was revolutionized and simplified in 1926 by the French designer Coco Chanel, who published a drawing of a simple black dress in Vogue magazine. She famously said, "A woman needs just three things; a black dress, a black sweater, and, on her arm, a man she loves." French designer Jean Patou also followed suit by creating a black collection in 1929. Other designers contributed to the trend of the little black dress. The Italian designer Gianni Versace said, "Black is the quintessence of simplicity and elegance," and French designer Yves Saint Laurent said, "black is the liaison which connects art and fashion. One of the most famous black dresses of the century was designed by Hubert de Givenchy and was worn by Audrey Hepburn in the 1961 film Breakfast at Tiffany's.

The American civil rights movement in the 1950s was a struggle for the political equality of African Americans. It developed into the Black Power movement in the early 1960s until the late 1980s, and the Black Lives Matter movement in the 2010s and 2020s. It also popularized the slogan "Black is Beautiful".

Physics
In the visible spectrum, black is the result of the absorption of all light wavelengths. Black can be defined as the visual impression (or color) experienced when no visible light reaches the eye. Pigments or dyes that absorb light rather than reflect it back to the eye look black. A black pigment can, however, result from a combination of several pigments that collectively absorb all wavelengths of visible light. If appropriate proportions of three primary pigments are mixed, the result reflects so little light as to be called black. This provides two superficially opposite but actually complementary descriptions of black. Black is the color produced by the absorption of all wavelengths of visible light, or an exhaustive combination of multiple colors of pigment.

In physics, a black body is a perfect absorber of light, but, by a thermodynamic rule, it is also the best emitter. Thus, the best radiative cooling, out of sunlight, is by using black paint, though it is important that it be black (a nearly perfect absorber) in the infrared as well. In elementary science, far ultraviolet light is called "black light" because, while itself unseen, it causes many minerals and other substances to fluoresce.

Absorption of light is contrasted by transmission, reflection and diffusion, where the light is only redirected, causing objects to appear transparent, reflective or white respectively. A material is said to be black if most incoming light is absorbed equally in the material. Light (electromagnetic radiation in the visible spectrum) interacts with the atoms and molecules, which causes the energy of the light to be converted into other forms of energy, usually heat. This means that black surfaces can act as thermal collectors, absorbing light and generating heat (see Solar thermal collector).

As of September 2019, the darkest material is made from vertically aligned carbon nanotubes. The material was grown by MIT engineers and was reported to have a 99.995% absorption rate of any incoming light. This surpasses any former darkest materials including Vantablack, which has a peak absorption rate of 99.965% in the visible spectrum.

Pigments
The earliest pigments used by Neolithic man were charcoal, red ocher and yellow ocher. The black lines of cave art were drawn with the tips of burnt torches made of a wood with resin. Different charcoal pigments were made by burning different woods and animal products, each of which produced a different tone. The charcoal would be ground and then mixed with animal fat to make the pigment.
 * Vine black was produced in Roman times by burning the cut branches of grapevines. It could also be produced by burning the remains of the crushed grapes, which were collected and dried in an oven. According to the historian Vitruvius, the deepness and richness of the black produced corresponded to the quality of the wine. The finest wines produced a black with a bluish tinge the color of indigo.

The 15th-century painter Cennino Cennini described how this pigment was made during the Renaissance in his famous handbook for artists: "...there is a black which is made from the tendrils of vines. And these tendrils need to be burned. And when they have been burned, throw some water onto them and put them out and then mull them in the same way as the other black. And this is a lean and black pigment and is one of the perfect pigments that we use."

Cennini also noted that "There is another black which is made from burnt almond shells or peaches and this is a perfect, fine black." Similar fine blacks were made by burning the pits of the peach, cherry or apricot. The powdered charcoal was then mixed with gum arabic or the yellow of an egg to make a paint.

Different civilizations burned different plants to produce their charcoal pigments. The Inuit of Alaska used wood charcoal mixed with the blood of seals to paint masks and wooden objects. The Polynesians burned coconuts to produce their pigment.
 * Lamp black was used as a pigment for painting and frescoes, as a dye for fabrics, and in some societies for making tattoos. The 15th century Florentine painter Cennino Cennini described how it was made during the Renaissance:  "... take a lamp full of linseed oil and fill the lamp with the oil and light the lamp. Then place it, lit, under a thoroughly clean pan and make sure that the flame from the lamp is two or three fingers from the bottom of the pan. The smoke that comes off the flame will hit the bottom of the pan and gather, becoming thick. Wait a bit. take the pan and brush this pigment (that is, this smoke) onto paper or into a pot with something. And it is not necessary to mull or grind it because it is a very fine pigment. Re-fill the lamp with the oil and put it under the pan like this several times and, in this way, make as much of it as is necessary." This same pigment was used by Indian artists to paint the Ajanta Caves, and as dye in ancient Japan.
 * Ivory black, also known as bone char, was originally produced by burning ivory and mixing the resulting charcoal powder with oil. The color is still made today, but ordinary animal bones are substituted for ivory.
 * Mars black is a black pigment made of synthetic iron oxides. It is commonly used in water-colors and oil painting. It takes its name from Mars, the god of war and patron of iron.

Dyes
Good-quality black dyes were not known until the middle of the 14th century. The most common early dyes were made from bark, roots or fruits of different trees; usually walnuts, chestnuts, or certain oak trees. The blacks produced were often more gray, brown or bluish. The cloth had to be dyed several times to darken the color. One solution used by dyers was add to the dye some iron filings, rich in iron oxide, which gave a deeper black. Another was to first dye the fabric dark blue, and then to dye it black.

A much richer and deeper black dye was eventually found made from the oak apple or "gall-nut". The gall-nut is a small round tumor which grows on oak and other varieties of trees. They range in size from 2–5 cm, and are caused by chemicals injected by the larva of certain kinds of gall wasp in the family Cynipidae. The dye was very expensive; a great quantity of gall-nuts were needed for a very small amount of dye. The gall-nuts which made the best dye came from Poland, eastern Europe, the near east and North Africa. Beginning in about the 14th century, dye from gall-nuts was used for clothes of the kings and princes of Europe.

Another important source of natural black dyes from the 17th century onwards was the logwood tree, or Haematoxylum campechianum, which also produced reddish and bluish dyes. It is a species of flowering tree in the legume family, Fabaceae, that is native to southern Mexico and northern Central America. The modern nation of Belize grew from 17th century English logwood logging camps.

Since the mid-19th century, synthetic black dyes have largely replaced natural dyes. One of the important synthetic blacks is Nigrosin, a mixture of synthetic black dyes (CI 50415, Solvent black 5) made by heating a mixture of nitrobenzene, aniline and aniline hydrochloride in the presence of a copper or iron catalyst. Its main industrial uses are as a colorant for lacquers and varnishes and in marker-pen inks.

Inks
The first known inks were made by the Chinese, and date back to the 23rd century B.C. They used natural plant dyes and minerals such as graphite ground with water and applied with an ink brush. Early Chinese inks similar to the modern inkstick have been found dating to about 256 BC at the end of the Warring States period. They were produced from soot, usually produced by burning pine wood, mixed with animal glue. To make ink from an inkstick, the stick is continuously ground against an inkstone with a small quantity of water to produce a dark liquid which is then applied with an ink brush. Artists and calligraphists could vary the thickness of the resulting ink by reducing or increasing the intensity and time of ink grinding. These inks produced the delicate shading and subtle or dramatic effects of Chinese brush painting.

India ink (or "Indian ink" in British English) is a black ink once widely used for writing and printing and now more commonly used for drawing, especially when inking comic books and comic strips. The technique of making it probably came from China. India ink has been in use in India since at least the 4th century BC, where it was called masi. In India, the black color of the ink came from bone char, tar, pitch and other substances.

The ancient Romans had a black writing ink they called atramentum librarium. Its name came from the Latin word atrare, which meant to make something black. (This was the same root as the English word atrocious.) It was usually made, like India ink, from soot, although one variety, called atramentum elephantinum, was made by burning the ivory of elephants.

Gall-nuts were also used for making fine black writing ink. Iron gall ink (also known as iron gall nut ink or oak gall ink) was a purple-black or brown-black ink made from iron salts and tannic acids from gall nut. It was the standard writing and drawing ink in Europe, from about the 12th century to the 19th century, and remained in use well into the 20th century.

Astronomy

 * A black hole is a region of spacetime where gravity prevents anything, including light, from escaping. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically defined boundary called an event horizon that marks the point of no return. It is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics. Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses may form. There is general consensus that supermassive black holes exist in the centers of most galaxies. Although a black hole itself is black, infalling material forms an accretion disk, one of the brightest types of object in the universe.
 * Black-body radiation refers to the radiation coming from a body at a given temperature where all incoming energy (light) is converted to heat.
 * Black sky refers to the appearance of space as one emerges from Earth's atmosphere.

Why the night sky and space are black – Olbers' paradox
The fact that outer space is black is sometimes called Olbers' paradox. In theory, because the universe is full of stars, and is believed to be infinitely large, it would be expected that the light of an infinite number of stars would be enough to brilliantly light the whole universe all the time. However, the background color of outer space is black. This contradiction was first noted in 1823 by German astronomer Heinrich Wilhelm Matthias Olbers, who posed the question of why the night sky was black.

The current accepted answer is that, although the universe may be infinitely large, it is not infinitely old. It is thought to be about 13.8 billion years old, so we can only see objects as far away as the distance light can travel in 13.8 billion years. Light from stars farther away has not reached Earth, and cannot contribute to making the sky bright. Furthermore, as the universe is expanding, many stars are moving away from Earth. As they move, the wavelength of their light becomes longer, through the Doppler effect, and shifts toward red, or even becomes invisible. As a result of these two phenomena, there is not enough starlight to make space anything but black.

The daytime sky on Earth is blue because light from the Sun strikes molecules in Earth's atmosphere scattering light in all directions. Blue light is scattered more than other colors, and reaches the eye in greater quantities, making the daytime sky appear blue. This is known as Rayleigh scattering.

The nighttime sky on Earth is black because the part of Earth experiencing night is facing away from the Sun, the light of the Sun is blocked by Earth itself, and there is no other bright nighttime source of light in the vicinity. Thus, there is not enough light to undergo Rayleigh scattering and make the sky blue. On the Moon, on the other hand, because there is virtually no atmosphere to scatter the light, the sky is black both day and night. This also holds true for other locations without an atmosphere, such as Mercury.

Culture
In China, the color black is associated with water, one of the five fundamental elements believed to compose all things; and with winter, cold, and the direction north, usually symbolized by a black tortoise. It is also associated with disorder, including the positive disorder which leads to change and new life. When the first emperor of China Qin Shi Huang seized power from the Zhou dynasty, he changed the Imperial color from red to black, saying that black extinguished red. Only when the Han dynasty appeared in 206 BC was red restored as the imperial color.

In Japan, black is associated with mystery, the night, the unknown, the supernatural, the invisible and death. Combined with white, it can symbolize intuition. In 10th- and 11th-century Japan, it was believed that wearing black could bring misfortune. It was worn at court by those who wanted to set themselves apart from the established powers or who had renounced material possessions.

In Japan black can also symbolize experience, as opposed to white, which symbolizes naiveté. The black belt in martial arts symbolizes experience, while a white belt is worn by novices. Japanese men traditionally wear a black kimono with some white decoration on their wedding day.

Black is associated with depth in Indonesia, as well as the subterranean world, demons, disaster, and the left hand. When combined with white, however, it symbolizes harmony and equilibrium.

Anarchism
Anarchism is a political philosophy, most popular in the late 19th and early 20th centuries, which holds that governments and capitalism are harmful and undesirable. The symbols of anarchism was usually either a black flag or a black letter A. More recently it is usually represented with a bisected red and black flag, to emphasise the movement's socialist roots in the First International. Anarchism was most popular in Spain, France, Italy, Ukraine and Argentina. There were also small but influential movements in the United States, Russia and many other countries all around the world.

Fascism
The Blackshirts (camicie nere, 'CCNN) were Fascist paramilitary groups in Italy during the period immediately following World War I and until the end of World War II. The Blackshirts were officially known as the Voluntary Militia for National Security (Milizia Volontaria per la Sicurezza Nazionale, or MVSN).

Inspired by the black uniforms of the Arditi, Italy's elite storm troops of World War I, the Fascist Blackshirts were organized by Benito Mussolini as the military tool of his political movement. They used violence and intimidation against Mussolini's opponents. The emblem of the Italian fascists was a black flag with fasces, an axe in a bundle of sticks, an ancient Roman symbol of authority. Mussolini came to power in 1922 through his March on Rome with the blackshirts.

Black was also adopted by Adolf Hitler and the Nazis in Germany. Red, white and black were the colors of the flag of the German Empire from 1870 to 1918. In Mein Kampf, Hitler explained that they were "revered colors expressive of our homage to the glorious past." Hitler also wrote that "the new flag ... should prove effective as a large poster" because "in hundreds of thousands of cases a really striking emblem may be the first cause of awakening interest in a movement." The black swastika was meant to symbolize the Aryan race, which, according to the Nazis, "was always anti-Semitic and will always be anti-Semitic." Several designs by a number of different authors were considered, but the one adopted in the end was Hitler's personal design. Black became the color of the uniform of the SS, the Schutzstaffel or "defense corps", the paramilitary wing of the Nazi Party, and was worn by SS officers from 1932 until the end of World War II.

The Nazis used a black triangle to symbolize anti-social elements. The symbol originates from Nazi concentration camps, where every prisoner had to wear one of the Nazi concentration camp badges on their jacket, the color of which categorized them according to "their kind". Many Black Triangle prisoners were either mentally disabled or mentally ill. The homeless were also included, as were alcoholics, the Romani people, the habitually "work-shy", prostitutes, draft dodgers and pacifists. More recently the black triangle has been adopted as a symbol in lesbian culture and by disabled activists.

Black shirts were also worn by the British Union of Fascists before World War II, and members of fascist movements in the Netherlands.

Patriotic resistance
The Lützow Free Corps, composed of volunteer German students and academics fighting against Napoleon in 1813, could not afford to make special uniforms and therefore adopted black, as the only color that could be used to dye their civilian clothing without the original color showing. In 1815 the students began to carry a red, black and gold flag, which they believed (incorrectly) had been the colors of the Holy Roman Empire (the imperial flag had actually been gold and black). In 1848, this banner became the flag of the German confederation. In 1866, Prussia unified Germany under its rule, and imposed the red, white and black of its own flag, which remained the colors of the German flag until the end of the Second World War. In 1949 the Federal Republic of Germany returned to the original flag and colors of the students and professors of 1815, which is the flag of Germany today.

Military
Black has been a traditional color of cavalry and armoured or mechanized troops. German armoured troops (Panzerwaffe) traditionally wore black uniforms, and even in others, a black beret is common. In Finland, black is the symbolic color for both armoured troops and combat engineers, and military units of these specialities have black flags and unit insignia.

The black beret and the color black is also a symbol of special forces in many countries. Soviet and Russian OMON special police and Russian naval infantry wear a black beret. A black beret is also worn by military police in the Canadian, Czech, Croatian, Portuguese, Spanish and Serbian armies.

The silver-on-black skull and crossbones symbol or Totenkopf and a black uniform were used by Hussars and Black Brunswickers, the German Panzerwaffe and the Nazi Schutzstaffel, and U.S. 400th Missile Squadron (crossed missiles), and continues in use with the Estonian Kuperjanov Battalion.

Religion
In Christian theology, black was the color of the universe before God created light. In many religious cultures, from Mesoamerica to Oceania to India and Japan, the world was created out of a primordial darkness. In the Bible the light of faith and Christianity is often contrasted with the darkness of ignorance and paganism.

In Christianity, the devil is often called the "prince of darkness". The term was used in John Milton's poem Paradise Lost, published in 1667, referring to Satan, who is viewed as the embodiment of evil. It is an English translation of the Latin phrase princeps tenebrarum, which occurs in the Acts of Pilate, written in the fourth century, in the 11th-century hymn Rhythmus de die mortis by Pietro Damiani, and in a sermon by Bernard of Clairvaux from the 12th century. The phrase also occurs in King Lear by William Shakespeare (c. 1606), Act III, Scene IV, l. 14: 'The prince of darkness is a gentleman."

Priests and pastors of the Roman Catholic, Eastern Orthodox and Protestant churches commonly wear black, as do monks of the Benedictine Order, who consider it the color of humility and penitence.
 * In Islam, black, along with green, plays an important symbolic role. It is the color of the Black Standard, the banner that is said to have been carried by the soldiers of Muhammad. It is also used as a symbol in Shi'a Islam (heralding the advent of the Mahdi), and the flag of followers of Islamism and Jihadism.
 * In Hinduism, the goddess Kali, goddess of time and change, is portrayed with black or dark blue skin. wearing a necklace adorned with severed heads and hands. Her name means "The black one". She destroys anger and passion according to Hindu mythology and her devotees are supposed to abstain from meat or intoxication.  Kali does not eat meat, but it is the śāstra's injunction that those who are unable to give up meat-eating, they may sacrifice one goat, not cow, one small animal before the goddess Kali, on amāvāsya (new moon) day, night, not day, and they can eat it.
 * In Paganism, black represents dignity, force, stability, and protection. The color is often used to banish and release negative energies, or binding. An athame is a ceremonial blade often having a black handle, which is used in some forms of witchcraft.

Sports

 * The national rugby union team of New Zealand is called the All Blacks, in reference to their black outfits, and the color is also shared by other New Zealand national teams such as the Black Caps (cricket) and the Kiwis (rugby league).
 * Association football (soccer) referees traditionally wear all-black uniforms, however nowadays other uniform colors may also be worn.
 * In auto racing, a black flag signals a driver to go into the pits.
 * In baseball, "the black" refers to the batter's eye, a blacked out area around the center-field bleachers, painted black to give hitters a decent background for pitched balls.
 * A large number of teams have uniforms designed with black colors even when the team does not normally feature that color. Many feel the color sometimes imparts a psychological advantage in its wearers. Black is used by numerous professional and collegiate sports teams

Idioms and expressions

 * In general, the Negro race of African origin is called "Black", while the Caucasian race of European origin is called "White".
 * In the United States, "Black Friday" (the day after Thanksgiving Day, the fourth Thursday in November) is traditionally the busiest shopping day of the year. Many Americans are on holiday because of Thanksgiving, and many retailers open earlier and close later than normal, and offer special prices. The day's name originated in Philadelphia sometime before 1961, and originally was used to describe the heavy and disruptive downtown pedestrian and vehicle traffic which would occur on that day. Later an alternative explanation began to be offered: that "Black Friday" indicates the point in the year that retailers begin to turn a profit, or are "in the black", because of the large volume of sales on that day.
 * "In the black" means profitable. Accountants originally used black ink in ledgers to indicate profit, and red ink to indicate a loss.
 * Black Friday also refers to any particularly disastrous day on financial markets. The first Black Friday (1869), 24 September 1869, was caused by the efforts of two speculators, Jay Gould and James Fisk, to corner the gold market on the New York Gold Exchange.
 * A blacklist is a list of undesirable persons or entities (to be placed on the list is to be "blacklisted").
 * Black comedy is a form of comedy dealing with morbid and serious topics. The expression is similar to black humor or black humour.
 * A black mark against a person relates to something bad they have done.
 * A black mood is a bad one (cf Winston Churchill's clinical depression, which he called "my black dog").
 * Black market is used to denote the trade of illegal goods, or alternatively the illegal trade of otherwise legal items at considerably higher prices, e.g. to evade rationing.
 * Black propaganda is the use of known falsehoods, partial truths, or masquerades in propaganda to confuse an opponent.
 * Blackmail is the act of threatening someone to do something that would hurt them in some way, such as by revealing sensitive information about them, in order to force the threatened party to fulfill certain demands. Ordinarily, such a threat is illegal.
 * If the black eight-ball, in billiards, is sunk before all others are out of play, the player loses.
 * The black sheep of the family is the ne'er-do-well.
 * To blackball someone is to block their entry into a club or some such institution. In the traditional English gentlemen's club, members vote on the admission of a candidate by secretly placing a white or black ball in a hat. If upon the completion of voting, there was even one black ball amongst the white, the candidate would be denied membership, and he would never know who had "blackballed" him.
 * Black tea in the Western culture is known as "crimson tea" in Chinese and culturally influenced languages (紅 茶, Mandarin Chinese hóngchá; Japanese kōcha; Korean hongcha).
 * "The black" is a wildfire suppression term referring to a burned area on a wildfire capable of acting as a safety zone.
 * Black coffee refers to coffee without sugar or cream.

Mourning
In the West, black is commonly associated with mourning and bereavement, and usually worn at funerals and memorial services. In some traditional societies, for example in Greece and Italy, some widows wear black for the rest of their lives. In contrast, across much of Africa and parts of Asia like Vietnam, white is a color of mourning.

In Victorian England, the colors and fabrics of mourning were specified in an unofficial dress code: "non-reflective black paramatta and crape for the first year of deepest mourning, followed by nine months of dullish black silk, heavily trimmed with crape, and then three months when crape was discarded.  Paramatta was a fabric of combined silk and wool or cotton; crape was a harsh black silk fabric with a crimped appearance produced by heat.  Widows were allowed to change into the colors of half-mourning, such as gray and lavender, black and white, for the final six months."

A "black day" (or week or month) usually refers to tragic date. The Romans marked fasti days with white stones and nefasti days with black. The term is often used to remember massacres. Black months include the Black September in Jordan, when large numbers of Palestinians were killed, and Black July in Sri Lanka, the killing of members of the Tamil population by the Sinhalese government.

In the financial world, the term often refers to a dramatic drop in the stock market. For example, the Wall Street Crash of 1929, the stock market crash on 29 October 1929, which marked the start of the Great Depression, is nicknamed Black Tuesday, and was preceded by Black Thursday, a downturn on 24 October the previous week.

Darkness and evil
In western popular culture, black has long been associated with evil and darkness. It is the traditional color of witchcraft and black magic.

In the Book of Revelation, the last book in the New Testament of the Bible, the Four Horsemen of the Apocalypse are supposed to announce the Apocalypse before the Last Judgment. The horseman representing famine rides a black horse. The vampire of literature and films, such as Count Dracula of the Bram Stoker novel, dressed in black, and could only move at night. The Wicked Witch of the West in the 1939 film The Wizard of Oz became the archetype of witches for generations of children. Whereas witches and sorcerers inspired real fear in the 17th century, in the 21st century children and adults dressed as witches for Halloween parties and parades.

Power, authority and solemnity
Black is frequently used as a color of power, law and authority. In many countries judges and magistrates wear black robes. That custom began in Europe in the 13th and 14th centuries. Jurists, magistrates and certain other court officials in France began to wear long black robes during the reign of Philip IV of France (1285–1314), and in England from the time of Edward I (1271–1307). The custom spread to the cities of Italy at about the same time, between 1300 and 1320. The robes of judges resembled those worn by the clergy, and represented the law and authority of the King, while those of the clergy represented the law of God and authority of the church.

Until the 20th century most police uniforms were black, until they were largely replaced by a less menacing blue in France, the U.S. and other countries. In the United States, police cars are frequently Black and white. The riot control units of the Basque Autonomous Police in Spain are known as beltzak ("blacks") after their uniform.

Black today is the most common color for limousines and the official cars of government officials.

Black formal attire is still worn at many solemn occasions or ceremonies, from graduations to formal balls. Graduation gowns are copied from the gowns worn by university professors in the Middle Ages, which in turn were copied from the robes worn by judges and priests, who often taught at the early universities. The mortarboard hat worn by graduates is adapted from a square cap called a biretta worn by Medieval professors and clerics.

Functionality
In the 19th and 20th centuries, many machines and devices, large and small, were painted black, to stress their functionality. These included telephones, sewing machines, steamships, railroad locomotives, and automobiles. The Ford Model T, the first mass-produced car, was available only in black from 1914 to 1926. Of means of transportation, only airplanes were rarely ever painted black.

Black house paint is becoming more popular with Sherwin-Williams reporting that the color, Tricorn Black, was the 6th most popular exterior house paint color in Canada and the 12th most popular paint in the United States in 2018.

Ethnography

 * The term "black" is often used in the West to describe people whose skin is darker. In the United States, it is particularly used to describe African Americans. The terms for African Americans have changed over the years, as shown by the categories in the United States Census, taken every ten years.
 * In the first U.S. Census, taken in 1790, just four categories were used: Free White males, Free White females, other free persons, and slaves.
 * In the 1820 census the new category "colored" was added.
 * In the 1850 census, slaves were listed by owner, and a B indicated black, while an M indicated "mulatto".
 * In the 1890 census, the categories for race were white, black, mulatto, quadroon (a person one-quarter black); octoroon (a person one-eighth black), Chinese, Japanese, or American Indian.
 * In the 1930 census, anyone with any black blood was supposed to be listed as "Negro".
 * In the 1970 census, the category "Negro or black" was used for the first time.
 * In the 2000 and 2012 census, the category "Black or African-American" was used, defined as "a person having their origin in any of the racial groups in Africa." In the 2012 Census 12.1 percent of Americans identified themselves as Black or African-American.

Black is also commonly used as a racial description in the United Kingdom, since ethnicity was first measured in the 2001 census. The 2011 British census asked residents to describe themselves, and categories offered included Black, African, Caribbean, or Black British. Other possible categories were African British, African Scottish, Caribbean British and Caribbean Scottish. Of the total UK population in 2001, 1.0 percent identified themselves as Black Caribbean, 0.8 percent as Black African, and 0.2 percent as Black (others).

In Canada, census respondents can identify themselves as Black. In the 2006 census, 2.5 percent of the population identified themselves as black.

In Australia, the term black is not used in the census. In the 2006 census, 2.3 percent of Australians identified themselves as Aboriginal and/or Torres Strait Islanders.

In Brazil, the Brazilian Institute of Geography and Statistics (IBGE) asks people to identify themselves as branco (white), pardo (brown), preto (black), or amarelo (yellow). In 2008 6.8 percent of the population identified themselves as "preto".

Opposite of white

 * Black and white have often been used to describe opposites; particularly light and darkness and good and evil. In Medieval literature, the white knight usually represented virtue, the black knight something mysterious and sinister. In American westerns, the hero often wore a white hat, the villain a black hat.
 * In the original game of chess invented in Persia or India, the colors of the two sides were varied; a 12th-century Iranian chess set in the New York Metropolitan Museum of Art, has red and green pieces. But when the game was imported into Europe, the colors, corresponding to European culture, usually became black and white.
 * Studies have shown that something printed in black letters on white has more authority with readers than any other color of printing.
 * In philosophy and arguments, the issue is often described as black-and-white, meaning that the issue at hand is dichotomized (having two clear, opposing sides with no middle ground).

Conspiracy
Black is commonly associated with secrecy.
 * The Black Chamber was a term given to an office which secretly opened and read diplomatic mail and broke codes. Queen Elizabeth I had such an office, headed by her Secretary, Sir Francis Walsingham, which successfully broke the Spanish codes and broke up several plots against the Queen. In France a cabinet noir was established inside the French post office by Louis XIII to open diplomatic mail. It was closed during the French Revolution but re-opened under Napoleon I. The Habsburg Empire and Dutch Republic had similar black chambers.
 * The United States created a secret peacetime Black Chamber, called the Cipher Bureau, in 1919. It was funded by the State Department and Army and disguised as a commercial company in New York. It successfully broke a number of diplomatic codes, including the code of the Japanese government. It was closed down in 1929 after the State Department withdrew funding, when the new Secretary of State, Henry Stimson, stated that "Gentlemen do not read each other's mail." The Cipher Bureau was the ancestor of the U.S. National Security Agency.
 * A black project is a secret unacknowledged military project, such as Enigma Decryption during World War II, or a secret counter-narcotics or police sting operation.
 * Black ops are covert operations carried out by a government, government agency or military.
 * A black budget is a government budget that is allocated for classified or other secret operations of a nation. The black budget is an account expenses and spending related to military research and covert operations. The black budget is mostly classified due to security reasons.

Elegant fashion
Black is the color most commonly associated with elegance in Europe and the United States, followed by silver, gold, and white.

Black first became a fashionable color for men in Europe in the 17th century, in the courts of Italy and Spain. (See history above.) In the 19th century, it was the fashion for men both in business and for evening wear, in the form of a black coat whose tails came down the knees. In the evening it was the custom of the men to leave the women after dinner to go to a special smoking room to enjoy cigars or cigarettes. This meant that their tailcoats eventually smelled of tobacco. According to the legend, in 1865 Edward VII, then the Prince of Wales, had his tailor make a special short smoking jacket. The smoking jacket then evolved into the dinner jacket. Again according to legend, the first Americans to wear the jacket were members of the Tuxedo Club in New York State. Thereafter the jacket became known as a tuxedo in the U.S. The term "smoking" is still used today in Russia and other countries. The tuxedo was always black until the 1930s, when the Duke of Windsor began to wear a tuxedo that was a very dark midnight blue. He did so because a black tuxedo looked greenish in artificial light, while a dark blue tuxedo looked blacker than black itself.

For women's fashion, the defining moment was the invention of the simple black dress by Coco Chanel in 1926. (See history.) Thereafter, a long black gown was used for formal occasions, while the simple black dress could be used for everything else. The designer Karl Lagerfeld, explaining why black was so popular, said: "Black is the color that goes with everything. If you're wearing black, you're on sure ground." Skirts have gone up and down and fashions have changed, but the black dress has not lost its position as the essential element of a woman's wardrobe. The fashion designer Christian Dior said, "elegance is a combination of distinction, naturalness, care and simplicity," and black exemplified elegance.

The expression "X is the new black" is a reference to the latest trend or fad that is considered a wardrobe basic for the duration of the trend, on the basis that black is always fashionable. The phrase has taken on a life of its own and has become a cliché.

Many performers of both popular and European classical music, including French singers Edith Piaf and Juliette Gréco, and violinist Joshua Bell have traditionally worn black on stage during performances. A black costume was usually chosen as part of their image or stage persona, or because it did not distract from the music, or sometimes for a political reason. Country-western singer Johnny Cash always wore black on stage. In 1971, Cash wrote the song "Man in Black" to explain why he dressed in that color: "We're doing mighty fine I do suppose / In our streak of lightning cars and fancy clothes / But just so we're reminded of the ones who are held back / Up front there ought to be a man in black."

title: Black


text:
Black Flag

Black Flag or black flag may refer to:

Flags

 * The Black Standard, a legendary flag in Islamic tradition
 * The Anarchist black flag
 * The Jolly Roger, flag associated with piracy
 * The Pan-African flag, a trans-national unity symbol
 * Black flag (racing)

Arts, entertainment, and media

 * Black Flag (band), an American hardcore punk band
 * Black Flag (comics), a comic book superhero team from Maximum Press
 * Black Flag (Ektomorf album), a 2012 album by Ektomorf
 * Black Flag (Machine Gun Kelly mixtape), 2013
 * "Black Flag" (song), a 1992 song by King's X
 * Black Flag (newspaper), a publication in Britain
 * Assassin's Creed IV: Black Flag, 2013 videogame by Ubisoft
 * Black Flags: The Rise of ISIS, a 2015 Pulitzer prize-winning book by Joby Warrick

Places

 * Black Flag, Western Australia, an abandoned town named after the Black Flag gold mine and farm

Other uses

 * Ali Charaf Damache, a terror suspect with the nom de guerre "the Black Flag"
 * Black Flag (insecticide)
 * Black Flag Army, a militia in Vietnam and southern China, 1860s-1885
 * Chernoe Znamia, a 20th-century Russian anarchist organisation
 * Ferraria crispa, a plant also known as black flag

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Black Flag


text:
Bletchley Park

Bletchley Park is an English country house and estate in Bletchley, Milton Keynes (Buckinghamshire), that became the principal centre of Allied code-breaking during the Second World War. The mansion was constructed during the years following 1883 for the financier and politician Herbert Leon in the Victorian Gothic, Tudor and Dutch Baroque styles, on the site of older buildings of the same name.

During World War II, the estate housed the Government Code and Cypher School (GC&CS), which regularly penetrated the secret communications of the Axis Powers – most importantly the German Enigma and Lorenz ciphers. The GC&CS team of codebreakers included Alan Turing, Harry Golombek, Gordon Welchman, Hugh Alexander, Bill Tutte and Stuart Milner-Barry.

According to the official historian of British Intelligence, the "Ultra" intelligence produced at Bletchley shortened the war by two to four years, and without it the outcome of the war would have been uncertain. The team at Bletchley Park devised automatic machinery to help with decryption, culminating in the development of Colossus, the world's first programmable digital electronic computer. Codebreaking operations at Bletchley Park came to an end in 1946 and all information about the wartime operations was classified until the mid-1970s.

After the war it had various uses including as a teacher-training college and local GPO headquarters. By 1990 the huts in which the codebreakers worked were being considered for demolition and redevelopment. The Bletchley Park Trust was formed in February 1992 to save large portions of the site from development.

More recently, Bletchley Park has been open to the public, featuring interpretive exhibits and huts that have been rebuilt to appear as they did during their wartime operations. It receives hundreds of thousands of visitors annually. The separate National Museum of Computing, which includes a working replica Bombe machine and a rebuilt Colossus computer, is housed in Block H on the site.

History
The site appears in the Domesday Book of 1086 as part of the Manor of Eaton. Browne Willis built a mansion there in 1711, but after Thomas Harrison purchased the property in 1793 this was pulled down. It was first known as Bletchley Park after its purchase by the architect Samuel Lipscomb Seckham in 1877, who built a house there. The estate of 581 acres was bought in 1883 by Sir Herbert Samuel Leon, who expanded the then-existing house into what architect Landis Gores called a "maudlin and monstrous pile" combining Victorian Gothic, Tudor, and Dutch Baroque styles. At his Christmas family gatherings there was a fox hunting meet on Boxing Day with glasses of sloe gin from the butler, and the house was always "humming with servants". With 40 gardeners, a flower bed of yellow daffodils could become a sea of red tulips overnight. After the death of Herbert Leon in 1926, the estate continued to be occupied by his widow Fanny Leon (née Higham) until her death in 1937.

In 1938, the mansion and much of the site was bought by a builder for a housing estate, but in May 1938 Admiral Sir Hugh Sinclair, head of the Secret Intelligence Service (SIS or MI6), bought the mansion and 58 acre of land for £6,000 (£ today) for use by GC&CS and SIS in the event of war. He used his own money as the Government said they did not have the budget to do so.

A key advantage seen by Sinclair and his colleagues (inspecting the site under the cover of "Captain Ridley's shooting party") was Bletchley's geographical centrality. It was almost immediately adjacent to Bletchley railway station, where the "Varsity Line" between Oxford and Cambridge – whose universities were expected to supply many of the code-breakers – met the main West Coast railway line connecting London, Birmingham, Manchester, Liverpool, Glasgow and Edinburgh. Watling Street, the main road linking London to the north-west (subsequently the A5) was close by, and high-volume communication links were available at the telegraph and telephone repeater station in nearby Fenny Stratford.

Bletchley Park was known as "B.P." to those who worked there. "Station X" (X = Roman numeral ten), "London Signals Intelligence Centre", and "Government Communications Headquarters" were all cover names used during the war. The formal posting of the many "Wrens" – members of the Women's Royal Naval Service – working there, was to HMS Pembroke V. Royal Air Force names of Bletchley Park and its outstations included RAF Eastcote, RAF Lime Grove and RAF Church Green. The postal address that staff had to use was "Room 47, Foreign Office".

After the war, the Government Code & Cypher School became the Government Communications Headquarters (GCHQ), moving to Eastcote in 1946 and to Cheltenham in the 1950s. The site was used by various government agencies, including the GPO and the Civil Aviation Authority. One large building, block F, was demolished in 1987 by which time the site was being run down with tenants leaving.

In 1990 the site was at risk of being sold for housing development. However, Milton Keynes Council made it into a conservation area. Bletchley Park Trust was set up in 1991 by a group of people who recognised the site's importance. The initial trustees included Roger Bristow, Ted Enever, Peter Wescombe, Dr Peter Jarvis of the Bletchley Archaeological & Historical Society, and Tony Sale who in 1994 became the first director of the Bletchley Park Museums.

Personnel

Admiral Hugh Sinclair was the founder and head of GC&CS between 1919 and 1938 with Commander Alastair Denniston being operational head of the organization from 1919 to 1942, beginning with its formation from the Admiralty's Room 40 (NID25) and the War Office's MI1b. Key GC&CS cryptanalysts who moved from London to Bletchley Park included John Tiltman, Dillwyn "Dilly" Knox, Josh Cooper, Oliver Strachey and Nigel de Grey. These people had a variety of backgrounds – linguists and chess champions were common, and Knox's field was papyrology. The British War Office recruited top solvers of cryptic crossword puzzles, as these individuals had strong lateral thinking skills.

On the day Britain declared war on Germany, Denniston wrote to the Foreign Office about recruiting "men of the professor type". Personal networking drove early recruitments, particularly of men from the universities of Cambridge and Oxford. Trustworthy women were similarly recruited for administrative and clerical jobs. In one 1941 recruiting stratagem, The Daily Telegraph was asked to organise a crossword competition, after which promising contestants were discreetly approached about "a particular type of work as a contribution to the war effort".

Denniston recognised, however, that the enemy's use of electromechanical cipher machines meant that formally trained mathematicians would also be needed; Oxford's Peter Twinn joined GC&CS in February 1939; Cambridge's Alan Turing and Gordon Welchman began training in 1938 and reported to Bletchley the day after war was declared, along with John Jeffreys. Later-recruited cryptanalysts included the mathematicians Derek Taunt, Jack Good, Bill Tutte, and Max Newman; historian Harry Hinsley, and chess champions Hugh Alexander and Stuart Milner-Barry. Joan Clarke was one of the few women employed at Bletchley as a full-fledged cryptanalyst.

When seeking to recruit more suitably advanced linguists, John Tiltman turned to Patrick Wilkinson of the Italian section for advice, and he suggested asking Lord Lindsay of Birker, of Balliol College, Oxford, S. W. Grose, and Martin Charlesworth, of St John's College, Cambridge, to recommend classical scholars or applicants to their colleges.

This eclectic staff of "Boffins and Debs" (scientists and debutantes, young women of high society) caused GC&CS to be whimsically dubbed the "Golf, Cheese and Chess Society".

During a morale-boosting visit on 9 September 1941, Winston Churchill reportedly remarked to Denniston or Menzies: "I told you to leave no stone unturned to get staff, but I had no idea you had taken me so literally." Six weeks later, having failed to get sufficient typing and unskilled staff to achieve the productivity that was possible, Turing, Welchman, Alexander and Milner-Barry wrote directly to Churchill. His response was "Action this day make sure they have all they want on extreme priority and report to me that this has been done."

After initial training at the Inter-Service Special Intelligence School set up by John Tiltman (initially at an RAF depot in Buckingham and later in Bedford – where it was known locally as "the Spy School") staff worked a six-day week, rotating through three shifts: 4 p.m. to midnight, midnight to 8 a.m. (the most disliked shift), and 8 a.m. to 4 p.m., each with a half-hour meal break. At the end of the third week, a worker went off at 8 a.m. and came back at 4 p.m., thus putting in 16 hours on that last day. The irregular hours affected workers' health and social life, as well as the routines of the nearby homes at which most staff lodged. The work was tedious and demanded intense concentration; staff got one week's leave four times a year, but some "girls" collapsed and required extended rest. Recruitment took place to combat a shortage of experts in Morse code and German.

In January 1945, at the peak of codebreaking efforts, nearly 10,000 personnel were working at Bletchley and its outstations. About three-quarters of these were women. Many of the women came from middle-class backgrounds and held degrees in the areas of mathematics, physics and engineering; they were given chance due to the lack of men, who had been sent to war. They performed calculations and coding and hence were integral to the computing processes. Among them were Eleanor Ireland, who worked on the Colossus computers and Ruth Briggs, a German scholar, who worked within the Naval Section.

The female staff in Dilwyn Knox's section were sometimes termed "Dilly's Fillies". Knox's methods enabled Mavis Lever (who married mathematician and fellow code-breaker Keith Batey) and Margaret Rock to solve a German code, the Abwehr cipher.

Many of the women had backgrounds in languages, particularly French, German and Italian. Among them were Rozanne Colchester, a translator who worked mainly for the Italian air forces Section, and Cicely Mayhew, recruited straight from university, who worked in Hut 8, translating decoded German Navy signals.

Alan Brooke (CIGS) in his secret wartime diary frequently refers to “intercepts”:

 * 16 April 1942: Took lunch in car and went to see the organization for breaking down ciphers [Bletchley Park] – a wonderful set of professors and genii! I marvel at the work they succeed in doing.

 * 28 June 1945: After lunch (with Andrew Cunningham (RN) and Sinclair (RAF) we went to “The Park” … I began by addressing some 400 of the workers who consist of all 3 services, both sexes, and civilians, They come from every sort of walk of life, professors, students, actors, dancers, mathematicians, electricians signallers, etc. I thanked them on behalf of the Chiefs of Staff and congratulated them on the results of their work. We then toured round the establishment and had tea before returning.

For a long time, the British Government failed to acknowledge the contributions the personnel at Bletchley Park had made. Their work achieved official recognition only in 2009.

Secrecy
Properly used, the German Enigma and Lorenz ciphers should have been virtually unbreakable, but flaws in German cryptographic procedures, and poor discipline among the personnel carrying them out, created vulnerabilities that made Bletchley's attacks just barely feasible. These vulnerabilities, however, could have been remedied by relatively simple improvements in enemy procedures, and such changes would certainly have been implemented had Germany had any hint of Bletchley's success. Thus the intelligence Bletchley produced was considered wartime Britain's "Ultra secret" – higher even than the normally highest classification Most Secret –and security was paramount.

All staff signed the Official Secrets Act (1939) and a 1942 security warning emphasised the importance of discretion even within Bletchley itself: "Do not talk at meals. Do not talk in the transport. Do not talk travelling. Do not talk in the billet. Do not talk by your own fireside. Be careful even in your Hut ..."

Nevertheless, there were security leaks. Jock Colville, the Assistant Private Secretary to Winston Churchill, recorded in his diary on 31 July 1941, that the newspaper proprietor Lord Camrose had discovered Ultra and that security leaks "increase in number and seriousness". Without doubt, the most serious of these was that Bletchley Park had been infiltrated by John Cairncross, the notorious Soviet mole and member of the Cambridge Spy Ring, who leaked Ultra material to Moscow.

Despite the high degree of secrecy surrounding Bletchley Park during the Second World War, unique and hitherto unknown amateur film footage of the outstation at nearby Whaddon Hall came to light in 2020, after being anonymously donated to the Bletchley Park Trust. A spokesman for the Trust noted the film's existence was all the more incredible because it was "very, very rare even to have [still] photographs" of the park and its associated sites.

Early work

The first personnel of the Government Code and Cypher School (GC&CS) moved to Bletchley Park on 15 August 1939. The Naval, Military, and Air Sections were on the ground floor of the mansion, together with a telephone exchange, teleprinter room, kitchen, and dining room; the top floor was allocated to MI6. Construction of the wooden huts began in late 1939, and Elmers School, a neighbouring boys' boarding school in a Victorian Gothic redbrick building by a church, was acquired for the Commercial and Diplomatic Sections.

After the United States joined World War II, a number of American cryptographers were posted to Hut 3, and from May 1943 onwards there was close co-operation between British and American intelligence. (See 1943 BRUSA Agreement.) In contrast, the Soviet Union was never officially told of Bletchley Park and its activities, a reflection of Churchill's distrust of the Soviets even during the US-UK-USSR alliance imposed by the Nazi threat.

The only direct enemy damage to the site was done 20–21 November 1940 by three bombs probably intended for Bletchley railway station; Hut 4, shifted two feet off its foundation, was winched back into place as work inside continued.

Intelligence reporting
Initially, when only a very limited amount of Enigma traffic was being read, deciphered non-Naval Enigma messages were sent from Hut 6 to Hut 3 which handled their translation and onward transmission. Subsequently, under Group Captain Eric Jones, Hut 3 expanded to become the heart of Bletchley Park's intelligence effort, with input from decrypts of "Tunny" (Lorenz SZ42) traffic and many other sources. Early in 1942 it moved into Block D, but its functions were still referred to as Hut 3.

Hut 3 contained a number of sections: Air Section "3A", Military Section "3M", a small Naval Section "3N", a multi-service Research Section "3G" and a large liaison section "3L". It also housed the Traffic Analysis Section, SIXTA. An important function that allowed the synthesis of raw messages into valuable Military intelligence was the indexing and cross-referencing of information in a number of different filing systems. Intelligence reports were sent out to the Secret Intelligence Service, the intelligence chiefs in the relevant ministries, and later on to high-level commanders in the field.

Naval Enigma deciphering was in Hut 8, with translation in Hut 4. Verbatim translations were sent to the Naval Intelligence Division (NID) of the Admiralty's Operational Intelligence Centre (OIC), supplemented by information from indexes as to the meaning of technical terms and cross-references from a knowledge store of German naval technology. Where relevant to non-naval matters, they would also be passed to Hut 3. Hut 4 also decoded a manual system known as the dockyard cipher, which sometimes carried messages that were also sent on an Enigma network. Feeding these back to Hut 8 provided excellent "cribs" for Known-plaintext attacks on the daily naval Enigma key.

Listening stations
Initially, a wireless room was established at Bletchley Park. It was set up in the mansion's water tower under the code name "Station X", a term now sometimes applied to the codebreaking efforts at Bletchley as a whole. The "X" is the Roman numeral "ten", this being the Secret Intelligence Service's tenth such station. Due to the long radio aerials stretching from the wireless room, the radio station was moved from Bletchley Park to nearby Whaddon Hall to avoid drawing attention to the site.

Subsequently, other listening stations – the Y-stations, such as the ones at Chicksands in Bedfordshire, Beaumanor Hall, Leicestershire (where the headquarters of the War Office "Y" Group was located) and Beeston Hill Y Station in Norfolk – gathered raw signals for processing at Bletchley. Coded messages were taken down by hand and sent to Bletchley on paper by motorcycle despatch riders or (later) by teleprinter.

Additional buildings
The wartime needs required the building of additional accommodation.

Huts
Often a hut's number became so strongly associated with the work performed inside that even when the work was moved to another building it was still referred to by the original "Hut" designation.
 * Hut 1: The first hut, built in 1939 used to house the Wireless Station for a short time, later administrative functions such as transport, typing, and Bombe maintenance. The first Bombe, "Victory", was initially housed here.
 * Hut 2: A recreational hut for "beer, tea, and relaxation".
 * Hut 3: Intelligence: translation and analysis of Army and Air Force decrypts
 * Hut 4: Naval intelligence: analysis of Naval Enigma and Hagelin decrypts
 * Hut 5: Military intelligence including Italian, Spanish, and Portuguese ciphers and German police codes.
 * Hut 6: Cryptanalysis of Army and Air Force Enigma
 * Hut 7: Cryptanalysis of Japanese naval codes and intelligence.
 * Hut 8: Cryptanalysis of Naval Enigma.
 * Hut 9: ISOS (Intelligence Section Oliver Strachey).
 * Hut 10: Secret Intelligence Service (SIS or MI6) codes, Air and Meteorological sections.
 * Hut 11: Bombe building.
 * Hut 14: Communications centre.
 * Hut 15: SIXTA (Signals Intelligence and Traffic Analysis).
 * Hut 16: ISK (Intelligence Service Knox) Abwehr ciphers.
 * Hut 18: ISOS (Intelligence Section Oliver Strachey).

 * Hut 23: Primarily used to house the engineering department. After February 1943, Hut 3 was renamed Hut 23.

Blocks
In addition to the wooden huts, there were a number of brick-built "blocks".
 * Block A: Naval Intelligence.
 * Block B: Italian Air and Naval, and Japanese code breaking.
 * Block C: Stored the substantial punch-card indexes.
 * Block D: From February 1943 it housed those from Hut 3, who synthesised intelligence from multiple sources, Huts 6 and 8 and SIXTA.
 * Block E: Incoming and outgoing Radio Transmission and TypeX.
 * Block F: Included the Newmanry and Testery, and Japanese Military Air Section. It has since been demolished.
 * Block G: Traffic analysis and deception operations.
 * Block H: Tunny and Colossus (now The National Museum of Computing).

German signals

Most German messages decrypted at Bletchley were produced by one or another version of the Enigma cipher machine, but an important minority were produced by the even more complicated twelve-rotor Lorenz SZ42 on-line teleprinter cipher machine used for high command messages, known as Fish.

Five weeks before the outbreak of war, Warsaw's Cipher Bureau revealed its achievements in breaking Enigma to astonished French and British personnel. The British used the Poles' information and techniques, and the Enigma clone sent to them in August 1939, which greatly increased their (previously very limited) success in decrypting Enigma messages.

The bombe was an electromechanical device whose function was to discover some of the daily settings of the Enigma machines on the various German military networks. Its pioneering design was developed by Alan Turing (with an important contribution from Gordon Welchman) and the machine was engineered by Harold 'Doc' Keen of the British Tabulating Machine Company. Each machine was about 7 ft high and wide, 2 ft deep and weighed about a ton.

At its peak, GC&CS was reading approximately 4,000 messages per day. As a hedge against enemy attack most bombes were dispersed to installations at Adstock and Wavendon (both later supplanted by installations at Stanmore and Eastcote), and Gayhurst.

Luftwaffe messages were the first to be read in quantity. The German navy had much tighter procedures, and the capture of code books was needed before they could be broken. When, in February 1942, the German navy introduced the four-rotor Enigma for communications with its Atlantic U-boats, this traffic became unreadable for a period of ten months. Britain produced modified bombes, but it was the success of the US Navy Bombe that was the main source of reading messages from this version of Enigma for the rest of the war. Messages were sent to and fro across the Atlantic by enciphered teleprinter links.

The Lorenz messages were codenamed Tunny at Bletchley Park. They were only sent in quantity from mid-1942. The Tunny networks were used for high-level messages between German High Command and field commanders. With the help of German operator errors, the cryptanalysts in the Testery (named after Ralph Tester, its head) worked out the logical structure of the machine despite not knowing its physical form. They devised automatic machinery to help with decryption, which culminated in Colossus, the world's first programmable digital electronic computer. This was designed and built by Tommy Flowers and his team at the Post Office Research Station at Dollis Hill. The prototype first worked in December 1943, was delivered to Bletchley Park in January and first worked operationally on 5 February 1944. Enhancements were developed for the Mark 2 Colossus, the first of which was working at Bletchley Park on the morning of 1 June in time for D-day. Flowers then produced one Colossus a month for the rest of the war, making a total of ten with an eleventh part-built. The machines were operated mainly by Wrens in a section named the Newmanry after its head Max Newman.

Bletchley's work was essential to defeating the U-boats in the Battle of the Atlantic, and to the British naval victories in the Battle of Cape Matapan and the Battle of North Cape. In 1941, Ultra exerted a powerful effect on the North African desert campaign against German forces under General Erwin Rommel. General Sir Claude Auchinleck wrote that were it not for Ultra, "Rommel would have certainly got through to Cairo". While not changing the events, "Ultra" decrypts featured prominently in the story of Operation SALAM, László Almásy's mission across the desert behind Allied lines in 1942. Prior to the Normandy landings on D-Day in June 1944, the Allies knew the locations of all but two of Germany's fifty-eight Western-front divisions.

Italian signals
Italian signals had been of interest since Italy's attack on Abyssinia in 1935. During the Spanish Civil War the Italian Navy used the K model of the commercial Enigma without a plugboard; this was solved by Knox in 1937. When Italy entered the war in 1940 an improved version of the machine was used, though little traffic was sent by it and there were "wholesale changes" in Italian codes and cyphers.

Knox was given a new section for work on Enigma variations, which he staffed with women ("Dilly's girls"), who included Margaret Rock, Jean Perrin, Clare Harding, Rachel Ronald, Elisabeth Granger; and Mavis Lever. Mavis Lever solved the signals revealing the Italian Navy's operational plans before the Battle of Cape Matapan in 1941, leading to a British victory.

Although most Bletchley staff did not know the results of their work, Admiral Cunningham visited Bletchley in person a few weeks later to congratulate them.

On entering World War II in June 1940, the Italians were using book codes for most of their military messages. The exception was the Italian Navy, which after the Battle of Cape Matapan started using the C-38 version of the Boris Hagelin rotor-based cipher machine, particularly to route their navy and merchant marine convoys to the conflict in North Africa. As a consequence, JRM Butler recruited his former student Bernard Willson to join a team with two others in Hut 4. In June 1941, Willson became the first of the team to decode the Hagelin system, thus enabling military commanders to direct the Royal Navy and Royal Air Force to sink enemy ships carrying supplies from Europe to Rommel's Afrika Korps. This led to increased shipping losses and, from reading the intercepted traffic, the team learnt that between May and September 1941 the stock of fuel for the Luftwaffe in North Africa reduced by 90 per cent. After an intensive language course, in March 1944 Willson switched to Japanese language-based codes.

A Middle East Intelligence Centre (MEIC) was set up in Cairo in 1939. When Italy entered the war in June 1940, delays in forwarding intercepts to Bletchley via congested radio links resulted in cryptanalysts being sent to Cairo. A Combined Bureau Middle East (CBME) was set up in November, though the Middle East authorities made "increasingly bitter complaints" that GC&CS was giving too little priority to work on Italian cyphers. However, the principle of concentrating high-grade cryptanalysis at Bletchley was maintained. John Chadwick started cryptanalysis work in 1942 on Italian signals at the naval base 'HMS Nile' in Alexandria. Later, he was with GC&CS; in the Heliopolis Museum, Cairo and then in the Villa Laurens, Alexandria.

Soviet signals
Soviet signals had been studied since the 1920s. In 1939–40, John Tiltman (who had worked on Russian Army traffic from 1930) set up two Russian sections at Wavendon (a country house near Bletchley) and at Sarafand in Palestine. Two Russian high-grade army and navy systems were broken early in 1940. Tiltman spent two weeks in Finland, where he obtained Russian traffic from Finland and Estonia in exchange for radio equipment. In June 1941, when the Soviet Union became an ally, Churchill ordered a halt to intelligence operations against it. In December 1941, the Russian section was closed down, but in late summer 1943 or late 1944, a small GC&CS Russian cypher section was set up in London overlooking Park Lane, then in Sloane Square.

Japanese signals
An outpost of the Government Code and Cypher School had been set up in Hong Kong in 1935, the Far East Combined Bureau (FECB). The FECB naval staff moved in 1940 to Singapore, then Colombo, Ceylon, then Kilindini, Mombasa, Kenya. They succeeded in deciphering Japanese codes with a mixture of skill and good fortune. The Army and Air Force staff went from Singapore to the Wireless Experimental Centre at Delhi, India.

In early 1942, a six-month crash course in Japanese, for 20 undergraduates from Oxford and Cambridge, was started by the Inter-Services Special Intelligence School in Bedford, in a building across from the main Post Office. This course was repeated every six months until war's end. Most of those completing these courses worked on decoding Japanese naval messages in Hut 7, under John Tiltman.

By mid-1945, well over 100 personnel were involved with this operation, which co-operated closely with the FECB and the US Signal intelligence Service at Arlington Hall, Virginia. In 1999, Michael Smith wrote that: "Only now are the British codebreakers (like John Tiltman, Hugh Foss, and Eric Nave) beginning to receive the recognition they deserve for breaking Japanese codes and cyphers".

Continued secrecy
After the War, the secrecy imposed on Bletchley staff remained in force, so that most relatives never knew more than that a child, spouse, or parent had done some kind of secret war work. Churchill referred to the Bletchley staff as "the geese that laid the golden eggs and never cackled". That said, occasional mentions of the work performed at Bletchley Park slipped the censor's net and appeared in print.

With the publication of F. W. Winterbotham's The Ultra Secret (1974) public discussion of Bletchley Park's work finally became possible, although even today some former staff still consider themselves bound to silence.

Professor Brian Randell was researching the history of computer science in Britain in 1975-76 for a conference on the history of computing held at the Los Alamos National Laboratory, New Mexico on 10–15 June 1976, and received permission to present a paper on wartime development of the COLOSSI at the Post Office Research Station,  Dollis Hill. (In October 1975 the British Government had released a series of captioned photographs from the Public Record Office.) The interest in the “revelations” in his paper resulted in a special evening meeting when Randell and Coombs answered further questions. Coombs later wrote that "no member of our team could ever forget the fellowship, the sense of purpose and, above all, the breathless excitement of those days". In 1977 Randell published an article "The First Electronic Computer" in several journals.

In July 2009 the British government announced that Bletchley personnel would be recognised with a commemorative badge.

Site
After the war, the site passed through a succession of hands and saw a number of uses, including as a teacher-training college and local GPO headquarters. By 1991, the site was nearly empty and the buildings were at risk of demolition for redevelopment.

In February 1992, the Milton Keynes Borough Council declared most of the Park a conservation area, and the Bletchley Park Trust was formed to maintain the site as a museum. The site opened to visitors in 1993, and was formally inaugurated by the Duke of Kent as Chief Patron in July 1994. In 1999 the land owners, the Property Advisors to the Civil Estate and BT, granted a lease to the Trust giving it control over most of the site.

Heritage attraction

June 2014 saw the completion of an £8 million restoration project by museum design specialist, Event Communications, which was marked by a visit from Catherine, Duchess of Cambridge. The Duchess' paternal grandmother, Valerie, and Valerie's twin sister, Mary (née Glassborow), both worked at Bletchley Park during the war. The twin sisters worked as Foreign Office Civilians in Hut 6, where they managed the interception of enemy and neutral diplomatic signals for decryption. Valerie married Catherine's grandfather, Captain Peter Middleton. A memorial at Bletchley Park commemorates Mary and Valerie Middleton's work as code-breakers.

Exhibitions

 * Block C Visitor Centre
 * Secrets Revealed introduction
 * The Road to Bletchley Park. Codebreaking in World War One.
 * Intel Security Cybersecurity exhibition. Online security and privacy in the 21st century.
 * Block B
 * Lorenz Cipher
 * Alan Turing
 * Enigma machines
 * Japanese codes
 * Home Front exhibition. How people lived in WW2
 * The Mansion
 * Office of Alistair Denniston
 * Library. Dressed as a World War II naval intelligence office
 * The Imitation Game exhibition
 * Gordon Welchman: Architect of Ultra Intelligence exhibition
 * Huts 3 and 6. Codebreaking offices as they would have looked during World War II.
 * Hut 8.
 * Interactive exhibitions explaining codebreaking
 * Alan Turing's office
 * Pigeon exhibition. The use of pigeons in World War II.
 * Hut 11. Life as a WRNS Bombe operator
 * Hut 12. Bletchley Park: Rescued and Restored. Items found during the restoration work.
 * Wartime garages
 * Hut 19. 2366 Bletchley Park Air Training Corp Squadron

Learning Department
The Bletchley Park Learning Department offers educational group visits with active learning activities for schools and universities. Visits can be booked in advance during term time, where students can engage with the history of Bletchley Park and understand its wider relevance for computer history and national security. Their workshops cover introductions to codebreaking, cyber security and the story of Enigma and Lorenz.

Funding
In October 2005, American billionaire Sidney Frank donated £500,000 to Bletchley Park Trust to fund a new Science Centre dedicated to Alan Turing. Simon Greenish joined as Director in 2006 to lead the fund-raising effort in a post he held until 2012 when Iain Standen took over the leadership role. In July 2008, a letter to The Times from more than a hundred academics condemned the neglect of the site. In September 2008, PGP, IBM and other technology firms announced a fund-raising campaign to repair the facility. On 6 November 2008 it was announced that English Heritage would donate £300,000 to help maintain the buildings at Bletchley Park, and that they were in discussions regarding the donation of a further £600,000.

In October 2011, the Bletchley Park Trust received a £4.6 million Heritage Lottery Fund grant to be used "to complete the restoration of the site, and to tell its story to the highest modern standards" on the condition that £1.7 million of match funding is raised by the Bletchley Park Trust. Just weeks later, Google contributed £550,000 and by June 2012 the trust had successfully raised £2.4 million to unlock the grants to restore Huts 3 and 6, as well as develop its exhibition centre in Block C.

Additional income is raised by renting Block H to the National Museum of Computing, and some office space in various parts of the park to private firms.

Due to the COVID-19 pandemic the Trust expected to lose more than £2 million in 2020 and be required to cut a third of its workforce. Former MP John Leech asked Amazon, Apple, Google, Facebook and Microsoft to donate £400,000 each to secure the future of the Trust. Leech had led the successful campaign to pardon Alan Turing and implement Turing's Law.

The National Museum of Computing

The National Museum of Computing is housed in Block H, which is rented from the Bletchley Park Trust. Its Colossus and Tunny galleries tell an important part of allied breaking of German codes during World War II. There is a working reconstruction of a Bombe and a rebuilt Colossus computer which was used on the high-level Lorenz cipher, codenamed Tunny by the British.

The museum, which opened in 2007, is an independent voluntary organisation that is governed by its own board of trustees. Its aim is "To collect and restore computer systems particularly those developed in Britain and to enable people to explore that collection for inspiration, learning and enjoyment." Through its many exhibits, the museum displays the story of computing through the mainframes of the 1960s and 1970s, and the rise of personal computing in the 1980s. It has a policy of having as many of the exhibits as possible in full working order.

Science and Innovation Centre
This consists of serviced office accommodation housed in Bletchley Park's Blocks A and E, and the upper floors of the Mansion. Its aim is to foster the growth and development of dynamic knowledge-based start-ups and other businesses.

Proposed National College of Cyber Security
In April 2020 Bletchley Park Capital Partners, a private company run by Tim Reynolds, Deputy Chairman of the National Museum of Computing, announced plans to sell off the freehold to part of the site containing former Block G for commercial development. Offers of between £4 million and £6 million were reportedly being sought for the 3 acre plot, for which planning permission for employment purposes was granted in 2005. Previously, the construction of a National College of Cyber Security for students aged from 16 to 19 years old had been envisaged on the site, to be housed in Block G after renovation with funds supplied by the Bletchley Park Science and Innovation Centre.

RSGB National Radio Centre
The Radio Society of Great Britain's National Radio Centre (including a library, radio station, museum and bookshop) are in a newly constructed building close to the main Bletchley Park entrance.

Final recognition

Not until July 2009 did the British government fully acknowledge the contribution of the many people working for the Government Code and Cypher School (G C & C S) at Bletchley. Only then was a commemorative medal struck to be presented to those involved. The gilded medal bears the inscription G C & C S 1939-1945 Bletchley Park and its Outstations.

Literature

 * Bletchley featured heavily in Robert Harris' novel Enigma (1995).
 * A fictionalised version of Bletchley Park is featured in Neal Stephenson's novel Cryptonomicon (1999).
 * Bletchley Park plays a significant role in Connie Willis' novel All Clear (2010).
 * The Agatha Christie novel N or M?, published in 1941, was about spies during the Second World War and featured a character called Major Bletchley. Christie was friends with one of the code-breakers at Bletchley Park, and MI5 thought that the character name might have been a joke indicating that she knew what was happening there. It turned out to be a coincidence.
 * Bletchley Park is the setting of Kate Quinn's 2021 historical fiction novel, The Rose Code. Quinn used the likenesses of true veterans of Bletchley Park as inspiration for her story of three women who worked in some of the different areas at Bletchley Park.

Film

 * The film Enigma (2001), which was based upon Robert Harris's book and starred Kate Winslet, Saffron Burrows and Dougray Scott, is set in part in Bletchley Park.
 * The film The Imitation Game (2014), starring Benedict Cumberbatch as Alan Turing, is set in Bletchley Park, and was partially filmed there.

Radio

 * The Radio Show Hut 33 is a Situation Comedy set in the fictional 33rd Hut of Bletchley Park.
 * The Big Finish Productions Doctor Who audio Criss-Cross, released in September 2015, features the Sixth Doctor working undercover in Bletchley Park to decode a series of strange alien signals that have hindered his TARDIS, the audio also depicting his first meeting with his new companion Constance Clarke.
 * The Bletchley Park Podcast began in August 2012, with new episodes being released approximately monthly. It features stories told by the codebreakers, staff and volunteers, audio from events and reports on the development of Bletchley Park.

Television

 * The 1979 ITV television serial Danger UXB featured the character Steven Mount, who was a codebreaker at Bletchley and was driven to a nervous breakdown (and eventual suicide) by the stressful and repetitive nature of the work.
 * In Foyle's War, Adam Wainwright (Samantha Stewart's fiancé, then husband), is a former Bletchley Park codebreaker.
 * The Second World War code-breaking sitcom pilot "Satsuma & Pumpkin" was recorded at Bletchley Park in 2003 and featured Bob Monkhouse, OBE in his last screen role. The BBC declined to produce the show and develop it further before creating effectively the same show on Radio 4 several years later, featuring some of the same cast, entitled Hut 33.
 * Bletchley came to wider public attention with the documentary series Station X (1999).
 * The 2012 ITV programme, The Bletchley Circle, is a set of murder mysteries set in 1952 and 1953. The protagonists are four female former Bletchley codebreakers, who use their skills to solve crimes. The pilot episode's opening scene was filmed on-site, and the set was asked to remain there for its close adaptation of historiography.
 * The 2018 programme, The Bletchley Circle: San Francisco, is a spin-off of The Bletchley Circle. It takes place in San Francisco and features two characters from the original series.
 * Ian McEwan's television play The Imitation Game (1980) concludes at Bletchley Park.
 * Bletchley Park was featured in the sixth and final episode of the BBC TV documentary The Secret War (1977), presented and narrated by William Woodard. This episode featured interviews with Gordon Welchman, Harry Golombek, Peter Calvocoressi, F. W. Winterbotham, Max Newman, Jack Good, and Tommy Flowers.
 * The Agent Carter season 2 episode "Smoke & Mirrors" reveals that Agent Peggy Carter worked at Bletchley Park early in the war before joining the Strategic Scientific Reserve.

Theatre

 * The play Breaking the Code (1986) is set at Bletchley Park.

Location
Bletchley Park is opposite Bletchley railway station. It is close to junctions 13 and 14 of the M1, about 50 mi northwest of London.

title: Bletchley Park