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Black-letter law

In common law legal systems, black-letter law refers to well-established legal rules that are no longer subject to reasonable dispute. Black-letter law can be contrasted with legal theory or unsettled legal issues.

History and etymology
In an 1831 case in the U.S. Supreme Court, Jackson ex dem. Bradstreet v. Huntington, the phrase "black letter" was used: "It is seldom that a case in our time savours so much of the black letter; but the course of decisions in New York renders it unavoidable...". The phrase "black-letter law" was used in the Pennsylvania Supreme Court case Naglee v. Ingersoll, 7 Pa. 185 (1847). The phrase does not apparently come directly from association with Black's Law Dictionary, which was first published in 1891. It may refer to the practice of setting law books and citing legal precedents in blackletter type, a tradition that survived long after the switch to Roman and italic text for other printed works. It may also be linked to the Black Book of the Admiralty published in the Kingdom of Great Britain and Ireland that collates at least 1,000 years of European-based laws of the sea and an authority for the High Court of Admiralty Court and maritime cases in the early modern period.

The phrase refers to a distillation of the common law into general and accepted legal principles. This can be seen in the quote above from the Supreme Court where the court is noting that while the black-letter law is clear, New York precedent deviates from the general principles.

In common law, the informal notion of black-letter law includes the basic principles of law generally accepted by the courts and/or embodied in the statutes of a particular jurisdiction. The letter of the law is its actual implementation, thereby demonstrating that black-letter laws are those statutes, rules, acts, laws, provisions, etc. that are or have been written down, codified, or indicated somewhere in legal texts throughout history of specific state law. This is often the case for many precedents that have been set in the common law.

An example of such a state within the common law jurisdiction, and using the black letter legal doctrine is Canada. Canada is a monarchical state, with its roots invested in Colonial England, and black-letter law is the principles of law accepted by the majority of judges in most provinces and territories. Sometimes it is referred to as "hornbook law" meaning treatise or textbook, often relied upon as authoritative, competent, and generally accepted in the field of Canadian law.

In lawyer lingo, hornbook law or black-letter law is a fundamental and well-accepted legal principle that does not require any further explanation, since a hornbook is a primer of basics. Law is the rule which establish that a principle, provision, references, inference, observation, etc. may not require further explanation or clarification when the very nature of them shows that they are basic and elementary.

Similar phrases
The phrase is nearly synonymous with the phrase "hornbook law". There are a number of venerable legal sources that distill the common law on various subjects known as restatement of the Law. The specific titles will be "The Restatement (First) of Contracts" or "The Restatement of Agency", etc. Each of these volumes is divided into sections that begin with a text in boldface that summarizes a basic rule on an aspect of the law of contracts, agency, etc. This "restatement" is followed by commentary and examples that expand on the principle stated.

Another synonymous term, usually used in the United Kingdom, is "trite law".

Examples
Examples of black-letter law include that the formation of a contract requires consideration, or that the registration of a trademark requires established use in the course of trade.

title: Black-letter law


text:
Blue law

Blue laws, also known as Sunday laws, Sunday trade laws, and Sunday closing laws, are laws restricting or banning certain activities on specified days, usually Sundays in the western world. The laws were adopted originally for religious reasons, specifically to promote the observance of the Christian day of worship, but since then have come to serve secular purposes as well.

Blue laws commonly ban certain business and recreational activities on Sundays and impose restrictions on the retail sale of hard goods and consumables, particularly alcoholic beverages. The laws also place limitations on a range of other endeavors, including travel, fashions, hunting, professional sports, stage performances, movie showings, and gambling. While less prevalent today, blue laws continue to be enforced in parts of the United States and Canada as well as in European countries, such as Austria, Germany, Norway, and Poland, where most stores are required to close on Sundays.

In the United States, the Supreme Court has upheld blue laws as constitutional, recognizing their religious origins but citing secular justifications that have resulted, most notably the provision of a day of rest for the general population. Meanwhile, various state courts have struck down the laws as either unenforceable or in violation of their states' constitutions. In response, state legislators have re-enacted certain Sunday laws to satisfy the rulings while allowing some of the other statutes to remain on the books with no intention to enforce them.

History
The Roman Emperor Constantine promulgated the first known law regarding prohibition of Sunday labour for apparent religion-associated reasons in A.D. 321:

"On the venerable Day of the Sun let the magistrates and people residing in cities rest, and let all workshops be closed."

The earliest laws in North America addressing Sunday activities and public behavior were enacted in the Jamestown Colony in 1619 by the first General Assembly of Virginia. Among the 70 laws passed by the assembly was a mandate requiring attendance by all colonists at both morning and afternoon worship services on Sundays. The laws adopted that year also included provisions addressing idleness, gambling, drunkenness, and excessive apparel. Similar laws aimed at keeping the Sabbath holy and regulating morals were soon adopted throughout the colonies.

The first known example of the phrase "blue laws" in print was in the March 3, 1755, edition of the New-York Mercury, in which the writer imagines a future newspaper praising the revival of "our [Connecticut's] old Blue Laws". In his 1781 book General History of Connecticut, the Reverend Samuel Peters (1735–1826) used the phrase to describe numerous laws adopted by 17th-century Puritans that prohibited various activities on Sunday, recreational as well as commercial. Beyond that, Peters' book is regarded as an unreliable account of the laws and probably was written to satirize their puritanical nature.

While the historical roots of Sunday trade laws in the United States are generally known, the origin of the term "blue laws" remains a mystery. According to a Time magazine editorial in 1961, the year the Supreme Court heard four cases on the issue, the color blue came to be associated with colonial laws in opposition to the red emblem of British royalty. Other explanations have been offered. One of the most widely circulated is that early blue laws adopted in Connecticut were printed on blue paper. However, no copies have been found that would support this claim and it is not deemed credible. A more plausible explanation, one that is gaining general acceptance, is that the laws adopted by Puritans were aimed at enforcing morality and thus were "blue-nosed", though the term "blue" may have been used in the vernacular of the times as a synonym for puritanism itself, in effect, overly strict.

As Protestant moral reformers organized the Sabbath reform in 19th-century America, calls for the enactment and enforcement of stricter Sunday laws developed. Numerous Americans were arrested for working, keeping an open shop, drinking alcohol, traveling, and engaging in recreational activities on Sundays. Erwin Fahlbusch and Geoffrey William Bromiley write that throughout their existence, organizations advocating first-day Sabbatarianism, such as the Lord's Day Alliance in North America and the Lord's Day Observance Society in the British Isles, were supported by labor unions in lobbying "to prevent secular and commercial interests from hampering freedom of worship and from exploiting workers".

In Canada, the Ligue du Dimanche, a Roman Catholic Sunday league, supported the Lord's Day Act in 1923 and promoted first-day Sabbatarian legislation. Beginning in the 1840s, workers, Jews, Seventh Day Baptists, freethinkers, and other groups began to organize opposition. Throughout the century, Sunday laws fueled church–state controversy, and as an issue that contributed to the emergence of modern American minority-rights politics. On the other hand, the more recent Dies Domini, written by Pope John Paul II in 1998, advocates Sunday legislation in that it protects civil servants and workers; the North Dakota Catholic Conference in 2011 likewise maintained that blue laws, in accordance with the Compendium of the Social Doctrine of the Church, "ensure that, for reasons of economic productivity, citizens are not denied time for rest and divine worship". Similarly, Chief Justice Earl Warren, while recognizing the partial religious origin of blue laws, acknowledged the "secular purpose they served by providing a benefit to workers at the same time that they enhanced labor productivity".

Europe
[[File:European countries with large supermarkets open on Sundays.png|thumb|A map of Europe providing an overview of Sunday shopping laws in each country

Green: Large supermarkets and shopping centers are generally open on Sundays. Blue: Large supermarkets are allowed to be open for no more than 6 hours on Sundays. Red: Large supermarkets are generally closed on Sundays.]]

Germany
The Ladenschlussgesetz "shop closing" laws on Sundays and public holidays are in effect, since 1956.

Denmark
In Denmark the closing laws restricting retail trade on Sundays have been abolished with effect from October 1, 2012. From then on retail trade is only restricted on public holidays (New Years Day, Maundy Thursday, Good Friday, Easter Sunday, Easter Monday, Day of Prayer, Ascension Day, Whit Sunday, Whit Monday, Christmas Day and Boxing Day) and on Constitution Day, Christmas Eve and New Year's Eve (on New Year's Eve from 3 pm only). On these days almost all shops will remain closed. Exempt are bakeries, DIYs, garden centres, gas stations and smaller supermarkets.

Before 1994
Prior to 1994, trading laws forbade sale of certain products on a Sunday; the distinction between those that could and could not be sold was increasingly seen as arbitrary, and the laws were inadequately enforced and widely flouted. For example, some supermarkets would treat the relatively modest fines arising as a business cost and open nonetheless.

Since 1994
The Sunday Trading Act 1994 relaxed restrictions on Sunday trading. This produced vocal opposition from bodies such as the Keep Sunday Special campaign, and the Lord's Day Observance Society: on religious grounds, on the grounds that it would increase consumerism, and that it would reduce shop assistants' weekend leisure time.

The legislation permits large shops (those with a relevant floor area in excess of 280 square metres; 3000 sq. ft.) to open for up to six hours on Sunday. Small shops, those with an area of below 280 square metres (3000 sq. ft.), are free to set their own Sunday trading times. Some large shops, such as off-licences, service stations and garages, are exempt from the restrictions.

Some very large shops (e.g. department stores) open for longer than six hours on a Sunday by allowing customers in to browse 30 minutes prior to allowing them to make a purchase, since the six-hour restriction only applies to time during which the shop may make sales.

Christmas Day and Easter Sunday are non-trading days. This applies even to garden centres, which earlier had been trading over Easter, but not to small shops (those with an area of below 280 square metres; 3000 sq. ft.).

Netherlands
Prior to 1996, shops were generally closed on Sundays. A new law regarding opening times changed that and leaves that decision mostly up to local municipalities.

The Zondagswet ("Sunday law"), a law on Sabbath desecration, is mainly to ensure that church services remain undisturbed on Sundays and Christian holidays. It forbids public festivities on a Sunday before 13:00, as well as making noise that carries farther than 200 m (yards), but activities that are unlikely to disturb church services are exempt.

Northern Ireland
Prior to 2008, no football was permitted to be played on Sundays by clubs affiliated to the Irish Football Association in Northern Ireland.

Shops with a floor area of over 280 m2 may only open from 1 to 6pm on Sundays.

In Belfast, public playgrounds were closed on Sundays until 1965. Swings in public parks were tied up and padlocked to prevent their use. Similar laws formerly applied to cinemas, pubs and parks.

Poland
Since 2007, blue laws were enacted and resulted in stores closing on the 13 state holidays in Poland – these are both religious and secular days of rest. In 2014, an initiative by the Law and Justice party failed to pass the reading in the Sejm to ban trading on Sundays and state holidays. However, since 2018, the ruling government and the President of Poland has signed a law that restricts store trading from March 1, 2018, to the first and last Sunday of the month, Palm Sunday, the 3rd and 4th Advent Sundays, as well as trading until 14.00 for Easter Saturday and Christmas Eve. In 2019, the restriction was extended, and trading was permitted solely on the last Sunday of the month, as well as Palm Sunday, the 3rd and 4th Advent Sundays, as well as trading until 14.00 for Easter Saturday and Christmas Eve. From 2020, stores may only be open on seven Sundays in the year: Palm Sunday, the 3rd and 4th Advent Sundays, the last Sunday of January, April, June and August as well as trading until 14.00 for Easter Saturday and Christmas Eve. As a result of restrictions in connection with the COVID-19 pandemic, the 2nd Advent Sunday was later added as a shopping day.

Canada

The Lord's Day Act, which since 1906 had prohibited business transactions from taking place on Sundays, was declared unconstitutional in the 1985 case R. v. Big M Drug Mart Ltd. Calgary police officers witnessed several transactions at the Big M Drug Mart, all of which occurred on a Sunday. Big M was charged with a violation of the Lord's Day Act. A provincial court ruled that the Lord's Day Act was unconstitutional, but the Crown proceeded to appeal all the way to the Supreme Court of Canada. In a unanimous 6–0 decision, the Lord's Day Act was ruled an infringement of the freedom of conscience and religion defined in section 2(a) of the Charter of Rights and Freedoms.

A Toronto referendum in 1950 allowed only team sports to be played professionally on Sunday. Theatre performances, movie screenings, and horse racing were not permitted until the 1960s.

The Supreme Court later concluded, in R. v. Edwards Books and Art Ltd. [1986] (2 S.C.R. 713), that Ontario's Retail Business Holiday Act, which required some Sunday closings, did not violate the Charter because it did not have a religious purpose. Nonetheless, as of today, virtually all provincial Sunday closing laws have ceased to exist. Some were struck down by provincial courts, but most were simply abrogated, often due to competitive reasons where out-of-province or foreign merchants were open.

United States
In the United States, judges have defended blue laws "in terms of their secular benefit to workers", holding that "the laws were essential to social well-being". In 1896, Supreme Court Justice Stephen Johnson Field, opined with regard to Sunday blue laws:

"Its requirement is a cessation from labor. In its enactment, the legislature has given the sanction of law to a rule of conduct, which the entire civilized world recognizes as essential to the physical and moral well-being of society. Upon no subject is there such a concurrence of opinion, among philosophers, moralists and statesmen of all nations, as on the necessity of periodical cessation from labor. One day in seven is the rule, founded in experience and sustained by science. ... The prohibition of secular business on Sunday is advocated on the ground that by it the general welfare is advanced, labor protected, and the moral and physical well-being of society promoted."

- Hennington v. Georgia, 163 U.S. 299 (1896)

Many states prohibit selling alcohol for on and off-premises sales in one form or another on Sundays at some restricted time, under the idea that people should be in church on Sunday morning, or at least not drinking.

Many blue laws in the United States restrict the purchase of particular items on Sundays. Some of these laws restrict the ability to buy cars, groceries, office supplies, and housewares among other things. Though most of these laws have been relaxed or repealed in most states, they are still enforced in some other states.

In Texas, for example, blue laws prohibited selling housewares such as pots, pans, and washing machines on Sunday until 1985. In Colorado, Illinois, Indiana, Iowa, Louisiana, Maine, Minnesota, Missouri, Oklahoma, New Jersey, North Dakota, Pennsylvania, and Wisconsin, car dealerships continue to operate under blue-law prohibitions in which an automobile may not be purchased or traded on a Sunday. Maryland permits Sunday automobile sales only in the counties of Charles, Prince George's, Montgomery, and Howard; similarly, Michigan restricts Sunday sales to only those counties with a population of less than 130,000. Texas and Utah prohibit car dealerships from operating over consecutive weekend days. In some cases, these laws were created or retained with the support of those whom they affected, to allow them a day off each week without fear of their competitors still being open.

Blue laws may also prohibit retail activity on days other than Sunday. In Massachusetts, Rhode Island, and Maine, for example, blue laws prohibit most retail stores, including grocery stores, from opening on Thanksgiving and Christmas.

Research regarding the effect of the repeal of blue laws has been conducted, with Professor Elesha Coffman of Baylor University writing: "Regarding culture, the impact of vanishing blue laws could be larger. A study in New Mexico in 2006 found a sharp increase in drunken driving on Sundays after that state dropped its Sunday ban on packaged alcohol sales. A broader study published by MIT and Notre Dame economists in 2008 found that the repeal of blue laws led to decreased church attendance, decreased donations to churches, and increased alcohol and drug use among religious individuals. These wide-ranging effects cannot easily be pinpointed to specific causes, but one of the latter study's authors, Daniel Hungerman, suggested to Christianity Today that blue laws might have been fulfilling their original intent, to keep people pious."

Court cases
Beginning in the mid-19th century, religious and ethno-cultural minorities arrested for violating state and local blue laws appealed their convictions to state supreme courts. In Specht v. Commonwealth (Pa. 1848), for example, German Seventh Day Baptists in Pennsylvania employed attorney Thaddeus Stevens to challenge the constitutionality of Pennsylvania's Sunday law. As in cases in other states, litigants pointed to the provisions of state constitutions protecting religious liberty and maintained that Sunday laws were a blatant violation. Though typically unsuccessful (most state supreme courts upheld the constitutionality of Sunday laws), these constitutional challenges helped set a pattern by which subsequent minorities would seek to protect religious freedom and minority rights.

The Supreme Court of the United States held in its landmark case, McGowan v. Maryland (1961), that Maryland's blue laws violated neither the Free Exercise Clause nor the Establishment Clause of the First Amendment to the United States Constitution. It approved the state's blue law restricting commercial activities on Sunday, noting that while such laws originated to encourage attendance at Christian churches, the contemporary Maryland laws were intended to serve "to provide a uniform day of rest for all citizens" on a secular basis and to promote the secular values of "health, safety, recreation, and general well-being" through a common day of rest. That this day coincides with Christian Sabbath is not a bar to the state's secular goals; it neither reduces its effectiveness for secular purposes nor prevents adherents of other religions from observing their own holy days.

McGowan was but one of four Sunday closing cases decided together by the Court in May 1961. In Gallagher v. Crown Kosher Super Market of Mass., Inc., the Court ruled against a Kosher deli that closed on Saturday but was open on Sunday. The other two cases were Braunfeld v. Brown, and Two Guys from Harrison-Allentown, Inc. v. McGinley. Chief Justice Earl Warren declared that "the State seeks to set one day apart from all others as a day of rest, repose, recreation and tranquility--a day which all members of the family and community have the opportunity to spend and enjoy together, a day on which there exists relative quiet and disassociation from the everyday intensity of commercial activities, a day on which people may visit friends and relatives who are not available during working days."

In March 2006, Texas judges upheld the state blue law that requires car dealerships to close either Saturday or Sunday each weekend.

Cook Islands and Niue
Blue laws also exist in the Polynesian islands of Cook Islands and Niue. In the Cook Islands, these were the first written legislation, enacted by the London Missionary Society in 1827, with the consent of the ariki (chiefs). Laws in Niue ban certain activities on Sunday, reflecting the country's history of observing the Christian Sabbath tradition.

Tonga
In the Kingdom of Tonga, the Vavaʻu Code (1839) was a form of blue law inspired by the teachings of Methodist missionaries. With the inauguration of the Tongan Constitution on June 4, 1875, the sixth clause stipulates: "The Sabbath Day shall be kept holy in Tonga and no person shall practise his trade or profession or conduct any commercial undertaking on the Sabbath Day except according to law; and any agreement made or witnessed on that day shall be null and void and of no legal effect."

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

title: Blue law


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Bar

Bar or BAR may refer to:

Food and drink

 * Bar (establishment), selling alcoholic beverages
 * Candy bar
 * Chocolate bar

 * Protein bar

Science and technology

 * Bar (river morphology), a deposit of sediment
 * Bar (tropical cyclone), a layer of cloud
 * Bar (unit), a unit of pressure
 * BAR domain, a protein domain
 * Bar stock, of metal
 * Sandbar

Computing

 * Bar (computer science), a placeholder
 * Base Address Register in PCI
 * Bar, a mobile phone form factor
 * Bar, a type of graphical control element

Law

 * Bar (law), the legal profession
 * Bar association
 * Bar examination

Media and entertainment

 * Bar (Croatian TV series)
 * Bar (Czech TV series)
 * Bar (dance), Turkey
 * Bar (music), a segment
 * Bar (Polish TV series)
 * Bar (Slovenian TV series)
 * Bay Area Reporter, a newspaper
 * Biblical Archaeology Review, a magazine
 * "Bar" (song), by Tini and L-Gante
 * B.A.R. (Bay Area Representatives), 2014 album by Lil Wyte and Frayser Boy

Places

 * Bar (Martian crater)
 * Bar, Rutog County, Tibet, China
 * Bar (river), France
 * Bar, Corrèze, France, a commune
 * Bar-le-Duc, France, a commune formerly Bar, Meuse
 * Bar-sur-Aube, France, a commune
 * Bar-sur-Seine, France, a commune
 * Bár, Hungary, a village
 * Bar, Bushehr, Iran, a village
 * Bar, Hormozgan, Iran, a village
 * Bar, Razavi Khorasan, Iran, a city
 * Bar Municipality, Montenegro
 * Bar, Montenegro, a town
 * Bar Region, Punjab, Pakistan
 * Bar, Republic of Buryatia, Russia
 * Bar, Vinnytsia Oblast, Ukraine, a town
 * Duchy of Bar, part of the Holy Roman Empire
 * Barbados, IOC and UNDP country code BAR

Language

 * Bar (diacritic), a line through a letter
 * Bavarian language (ISO 639-3: bar)
 * Vertical bar, a punctuation symbol
 * X-bar theory, in linguistics

Transportation

 * Bangor and Aroostook Railroad, US, reporting mark
 * Barstow station, US, station code
 * California Bureau of Automotive Repair, a consumer protection agency
 * Qionghai Bo'ao Airport, IATA code

Firearms

 * M1918 Browning Automatic Rifle
 * Browning BAR, a Belgian rifle

Other uses

 * Bar (Aramaic), a patronymic prefix in Aramaic
 * Bar (heraldry), a band across a shield
 * Bar (name)
 * Bar Confederation, an 18th-century Polish association
 * Bar Mitzvah, a Jewish coming of age ceremony
 * Blaauwberg Armoured Regiment, South African Army
 * British Archaeological Reports
 * British American Racing, a Formula One constructor
 * Chin-up bar, playground equipment
 * Medal bar, additional award
 * Space bar, on a keyboard
 * Historical gatehouse
 * Bennett acceptance ratio in thermodynamics
 * BlackArts Racing Team, a motor racing team from Hong Kong
 * Business Analysis and Reporting in the Uniform Certified Public Accountant Examination

title: Bar


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Beer

Beer is an alcoholic beverage produced by the brewing and fermentation of starches from cereal grains—most commonly malted barley, although wheat, maize (corn), rice, and oats are also used. The fermentation of the starch sugars in the wort produces ethanol and carbonation in the beer. Beer is one of the oldest alcoholic drinks in the world,  the most widely consumed, and the third most popular drink after water and tea. Most modern beer is brewed with hops, which add bitterness and other flavours and act as a natural preservative and stabilising agent. Other flavouring agents, such as gruit, herbs, or fruits, may be included or used instead of hops. In commercial brewing, natural carbonation is often replaced with forced carbonation.

Some of the earliest writings refer to the production and distribution of beer: the Code of Hammurabi included laws regulating it, and "The Hymn to Ninkasi", a prayer to the Mesopotamian goddess of beer, a recipe for it.

Beer is distributed in bottles and cans and is also commonly available on draught, particularly in pubs and bars. The brewing industry is a global business, consisting of several dominant multinational companies and many thousands of smaller producers ranging from brewpubs to regional breweries. The strength of modern beer is usually around 4% to 6% alcohol by volume (ABV).

Beer forms part of the culture of many nations and is associated with social traditions such as beer festivals, as well as activities like pub crawling, pub quizzes, and pub games.

Etymology

In early forms of English and in the Scandinavian languages, the usual word for beer was the word whose Modern English form is ale. The modern word beer comes into present-day English from Old English bēor, itself from Common Germanic, it is found throughout the West Germanic and North Germanic dialects (modern Dutch and German bier, Old Norse bjórr). The earlier etymology of the word is debated: the three main theories are that the word originates in Proto-Germanic *beuzą (putatively from Proto-Indo-European *bʰeusóm), meaning 'brewer's yeast, beer dregs'; that it is related to the word barley, or that it was somehow borrowed from Latin bibere 'to drink'. It is speculated by Christine Fell in Leeds Studies in English (1975), that the Old English/Norse word bēor did not denote ale or beer, but a strong, sweet drink rather like mead or cider; however, in Europe, the meaning of bēor expanded to cover the meaning of ale. When hopped ale from Europe was imported into Britain in the late Middle Ages using the word beer it was originally used to denote hopped ale to differentiate from the British unhopped ale, though later it came to mean all forms of beer.

History

Beer is one of the world's oldest prepared alcoholic drinks. The earliest archaeological evidence of fermentation consists of 13,000 year-old residues of a beer with the consistency of gruel, used by the semi-nomadic Natufians for ritual feasting, at the Raqefet Cave in the Carmel Mountains near Haifa in Israel. There is evidence that beer was produced at Göbekli Tepe during the Pre-Pottery Neolithic (around 8500 to 5500 ). The earliest clear chemical evidence of beer produced from barley dates to about 3500–3100, from the site of Godin Tepe in the Zagros Mountains of western Iran. It is possible, but not proven, that it dates back even further – to about 10,000, when cereal was first farmed.

Beer is recorded in the written history of ancient Egypt, and archaeologists speculate that beer was instrumental in the formation of civilizations. Approximately 5000 years ago, workers in the city of Uruk (modern day Iraq) were paid by their employers with volumes of beer. During the building of the Great Pyramids in Giza, Egypt, each worker got a daily ration of four to five litres of beer, which served as both nutrition and refreshment and was crucial to the pyramids' construction.

Some of the earliest Sumerian writings contain references to beer; examples include a prayer to the goddess Ninkasi, known as "The Hymn to Ninkasi", which served as both a prayer and a method of remembering the recipe for beer in a culture with few literate people, and the ancient advice ("Fill your belly. Day and night make merry") to Gilgamesh, recorded in the Epic of Gilgamesh by the alewife Siduri, may, at least in part, have referred to the consumption of beer. The Ebla tablets, discovered in 1974 in Ebla, Syria, show that beer was produced in the city in 2500 BC. A fermented drink using rice and fruit was made in China around 7000 BC. Unlike sake, mould was not used to saccharify the rice (amylolytic fermentation); the rice was probably prepared for fermentation by chewing or malting. During the Vedic period in Ancient India, there are records of the consumption of the beer-like sura. Xenophon noted that during his travels, beer was being produced in Armenia.

Almost any substance containing sugar can naturally undergo alcoholic fermentation and thus be utilised in the brewing of beer. It is likely that many cultures, on observing that a sweet liquid could be obtained from a source of starch, independently invented beer. Bread and beer increased prosperity to a level that allowed time for the development of other technologies and contributed to the building of civilizations.

Beer was spread through Europe by Germanic and Celtic tribes as far back as 3000 BC, and it was mainly brewed on a domestic scale. The product that the early Europeans drank might not be recognised as beer by most people today. Alongside the basic starch source, the early European beers may have contained fruits, honey, numerous types of plants, spices, and other substances such as narcotic herbs. What they did not contain was hops, as that was a later addition, first mentioned in Europe around 822 by a Carolingian Abbot and again in 1067 by abbess Hildegard of Bingen.

In 1516, William IV, Duke of Bavaria, adopted the Reinheitsgebot (purity law), perhaps the oldest food-quality regulation still in use in the 21st century, according to which the only allowed ingredients of beer are water, hops, and barley-malt. Beer produced before the Industrial Revolution continued to be made and sold on a domestic scale, although by the 7th century, beer was also being produced and sold by European monasteries. During the Industrial Revolution, the production of beer moved from artisanal manufacture to industrial manufacture, and domestic manufacture ceased to be significant by the end of the 19th century. The development of hydrometers and thermometers changed brewing by allowing the brewer more control of the process and greater knowledge of the results.

In 1912, brown bottles began to be used by the Joseph Schlitz Brewing Company of Milwaukee, Wisconsin, in the United States. This innovation has since been accepted worldwide as it prevents light rays from degrading the quality and stability of beer.

The brewing industry is now a global business, consisting of several dominant multinational companies and many thousands of smaller producers, ranging from brewpubs to regional breweries. As of 2006, more than 133 e9l, the equivalent of a cube 510 metres on a side, of beer are sold per year, producing total global revenues of US$294.5 billion. In 2010, China's beer consumption hit 450 e6hl, or nearly twice that of the United States, but only 5 per cent sold were premium beers, compared with 50 per cent in France and Germany.

A widely publicised study in 2018 suggested that sudden decreases in barley production due to extreme drought and heat could in the future cause substantial volatility in the availability and price of beer.

Brewing
The process of making beer is known as brewing. A dedicated building for the making of beer is called a brewery, though beer can be made at home and has been for much of its history, in which case the brewing location is often called a brewhouse. A company that makes beer is called either a brewery or a brewing company. Beer made on a domestic scale for non-commercial reasons is today usually classified as homebrewing, regardless of where it is made, though most homebrewed beer is made at home. Historically, domestic beer was what's called farmhouse ale.

Brewing beer has been subject to legislation and taxation for millennia, and from the late 19th century on, taxation largely restricted brewing to commercial operations only in the UK. However, the UK government relaxed legislation in 1963, followed by Australia in 1972 and the US in 1978, though individual states were allowed to pass their own laws limiting production, allowing homebrewing to become a popular hobby.

The purpose of brewing is to convert the starch source into a sugary liquid called wort and to convert the wort into the alcoholic drink known as beer in a fermentation process effected by yeast.

The first step, where the wort is prepared by mixing the starch source (normally malted barley) with hot water, is known as "mashing". Hot water (known as "liquor" in brewing terms) is mixed with crushed malt or malts (known as "grist") in a mash tun. The mashing process takes around 1 to 2 hours, during which the starches are converted to sugars, and then the sweet wort is drained off the grains. The grains are then washed in a process known as "sparging". This washing allows the brewer to gather as much of the fermentable liquid from the grains as possible. The process of filtering the spent grain from the wort and sparge water is called wort separation. The traditional process for wort separation is lautering, in which the grain bed itself serves as the filter medium. Some modern breweries prefer the use of filter frames, which allow for a more finely ground grist.

Most modern breweries use a continuous sparge, collecting the original wort and the sparge water together. However, it is possible to collect a second or even third wash with the not quite spent grains as separate batches. Each run would produce a weaker wort and thus, a weaker beer. This process is known as the second (and third) runnings. Brewing with several runnings is called parti gyle brewing.

The sweet wort collected from sparging is put into a kettle, or "copper" (so-called because these vessels were traditionally made from copper), and boiled, usually for about one hour. During boiling, the water in the wort evaporates, but the sugars and other components of the wort remain; this allows more efficient use of the starch sources in the beer. Boiling also destroys any remaining enzymes left over from the mashing stage. Hops are added during boiling as a source of bitterness, flavour, and aroma. Hops may be added at more than one point during the boil. The longer the hops are boiled, the more bitterness they contribute, but the less hop flavour and aroma remain in the beer.

After boiling, the hopped wort is cooled and ready for the yeast. In some breweries, the hopped wort may pass through a hopback, which is a small vat filled with hops, to add aromatic hop flavouring and to act as a filter, but usually the hopped wort is simply cooled for the fermenter, where the yeast is added. During fermentation, the wort becomes beer in a process that takes a week to several months, depending on the type of yeast and strength of the beer. In addition to producing ethanol, fine particulate matter suspended in the wort settles during fermentation. Once fermentation is complete, the yeast also settles, leaving the beer clear.

During fermentation, most of the carbon dioxide is allowed to escape through a trap, and the beer is left with carbonation of only about one atmosphere of pressure. The carbonation is often increased either by transferring the beer to a pressure vessel such as a keg and introducing pressurised carbon dioxide or by transferring it before the fermentation is finished so that carbon dioxide pressure builds up inside the container as the fermentation finishes. Sometimes the beer is put unfiltered (so it still contains yeast) into bottles with some added sugar, which then produces the desired amount of carbon dioxide inside the bottle.

Fermentation is sometimes carried out in two stages: primary and secondary. Once most of the alcohol has been produced during primary fermentation, the beer is transferred to a new vessel and allowed a period of secondary fermentation. Secondary fermentation is used when the beer requires long storage before packaging or greater clarity. When the beer has fermented, it is packaged either into casks for cask ale or kegs, aluminium cans, or bottles for other sorts of beer.

Ingredients

The basic ingredients of beer are water; a starch source, such as malted barley or malted maize (such as used in the preparation of Tiswin and Tesgüino), able to be saccharified (converted to sugars) and then fermented (converted into ethanol and carbon dioxide); a brewer's yeast to produce the fermentation; and a flavouring such as hops. A mixture of starch sources may be used, with a secondary carbohydrate source, such as maize (corn), rice, wheat, or sugar, often termed an adjunct, especially when used alongside malted barley. Less widely used starch sources include millet, sorghum, and cassava root in Africa; potato in Brazil; and agave in Mexico, among others. The amount of each starch source in a beer recipe is collectively called the grain bill.

Water is the main ingredient in beer, accounting for 93% of its weight. Though water itself is, ideally, flavourless, its level of dissolved minerals, specifically bicarbonate ions, does influence beer's finished taste. Due to the mineral properties of each region's water, specific areas were originally the sole producers of certain types of beer, each identifiable by regional characteristics. Regional geology accords that Dublin's hard water is well-suited to making stout, such as Guinness, while the Plzeň Region's soft water is ideal for brewing Pilsner (pale lager), such as Pilsner Urquell. The waters of Burton in England contain gypsum, which benefits making pale ale to such a degree that brewers of pale ales will add gypsum to the local water in a process known as Burtonisation.

The starch source, termed the "mash ingredients", in a beer provides the fermentable material and is a key determinant of the strength and flavour of the beer. The most common starch source used in beer is malted grain. Grain is malted by soaking it in water, allowing it to begin germination, and then drying the partially germinated grain in a kiln. Malting grain produces enzymes that convert starches in the grain into fermentable sugars. Different roasting times and temperatures are used to produce different colours of malt from the same grain. Darker malts will produce darker beers. Nearly all beers include barley malt as the majority of the starch. This is because its fibrous hull remains attached to the grain during threshing. After malting, barley is milled, which finally removes the hull, breaking it into large pieces. These pieces remain with the grain during the mash and act as a filter bed during lautering, when sweet wort is separated from insoluble grain material. Other malted and unmalted grains (including wheat, rice, oats, and rye, and less frequently, corn and sorghum) may be used. Some brewers have produced gluten-free beer, made with sorghum with no barley malt, for those who cannot consume gluten-containing grains like wheat, barley, and rye.

Flavouring beer is the sole major commercial use of hops. The flower of the hop vine is used as a flavouring and preservative agent in nearly all beer made today. The flowers themselves are often called "hops". The first historical mention of the use of hops in beer dates from 822 AD in monastery rules written by Adalhard the Elder, also known as Adalard of Corbie, though the date normally given for widespread cultivation of hops for use in beer is the thirteenth century. Before the thirteenth century and until the sixteenth century, during which hops took over as the dominant flavouring, beer was flavoured with other plants, for instance, grains of paradise or alehoof. Combinations of various aromatic herbs, berries, and even ingredients like wormwood would be combined into a mixture known as gruit and used as hops are now used. Some beers today, such as Fraoch' by the Scottish Heather Ales company and Cervoise Lancelot by the French Brasserie-Lancelot company, use plants other than hops for flavouring.

Hops contain several characteristics that brewers desire in beer. Hops contribute a bitterness that balances the sweetness of the malt; the bitterness of beers is measured on the International Bitterness Units scale. Hops contribute floral, citrus, and herbal aromas and flavours to beer. Hops have an antibiotic effect that favours the activity of brewer's yeast over less desirable microorganisms and aids in "head retention", the length of time that a foamy head created by carbonation will last. The acidity of hops is a preservative.

Yeast is the microorganism that is responsible for fermentation in beer. Yeast metabolises the sugars extracted from grains, which produce alcohol and carbon dioxide, and thereby turns wort into beer. In addition to fermenting the beer, yeast influences the character and flavour. The dominant types of yeast used to make beer are top-fermenting Saccharomyces cerevisiae and bottom-fermenting Saccharomyces pastorianus. Brettanomyces ferments lambics, and Torulaspora delbrueckii ferments Bavarian weissbier. Before the role of yeast in fermentation was understood, fermentation involved wild or airborne yeasts. A few styles, such as lambics, rely on this method today, but most modern fermentation adds pure yeast cultures.

Some brewers add one or more clarifying agents or finings to beer, which typically precipitate (collect as a solid) out of the beer along with protein solids and are found only in trace amounts in the finished product. This process makes the beer appear bright and clean, rather than the cloudy appearance of ethnic and older styles of beer, such as wheat beers. Examples of clarifying agents include isinglass, obtained from the swimbladders of fish; Irish moss, a seaweed; kappa carrageenan, from the seaweed Kappaphycus cottonii; Polyclar (artificial); and gelatin. If a beer is marked "suitable for vegans", it is clarified either with seaweed or with artificial agents.

Brewing industry

The history of breweries in the 21st century has included larger breweries absorbing smaller breweries in order to ensure economy of scale. In 2002, South African Breweries bought the North American Miller Brewing Company to found SABMiller, becoming the second-largest brewery after North American Anheuser-Busch. In 2004, the Belgian Interbrew was the third-largest brewery by volume, and the Brazilian AmBev was the fifth-largest. They merged into InBev, becoming the largest brewery. In 2007, SABMiller surpassed InBev and Anheuser-Busch when it acquired Royal Grolsch, the brewer of Dutch brand Grolsch. In 2008, when InBev (the second-largest) bought Anheuser-Busch (the third-largest), the new Anheuser-Busch InBev company became again the largest brewer in the world.

, according to the market research firm Technavio, AB InBev remains the largest brewing company in the world, with Heineken second, CR Snow third, Carlsberg fourth, and Molson Coors fifth.

A microbrewery, or craft brewery, produces a limited amount of beer. The maximum amount of beer a brewery can produce and still be classed as a 'microbrewery' varies by region and by authority; in the US, it is 15000 USbeerbbl a year. A brewpub is a type of microbrewery that incorporates a pub or other drinking establishment. The highest density of breweries in the world, most of them microbreweries, exists in Franconia, Germany, especially in the district of Upper Franconia, which has about 200 breweries. The Benedictine Weihenstephan brewery in Bavaria, Germany, can trace its roots to the year 768, as a document from that year refers to a hop garden in the area paying a tithe to the monastery. The brewery was licensed by the City of Freising in 1040 and is therefore the oldest working brewery in the world.

Varieties

While there are many types of beer brewed, the basics of brewing beer are shared across national and cultural boundaries. The traditional European brewing regions—Germany, Belgium, England and the Czech Republic—have local varieties of beer.

English writer Michael Jackson, in his 1977 book The World Guide To Beer, categorised beers from around the world in local style groups suggested by local customs and names. Fred Eckhardt furthered Jackson's work in The Essentials of Beer Style in 1989.

Top-fermented beers
Top-fermented beers are most commonly produced with Saccharomyces cerevisiae, a top-fermenting yeast which clumps and rises to the surface, typically between 15 and 25 C. At these temperatures, yeast produces significant amounts of esters and other secondary flavour and aroma products, and the result is often a beer with slightly "fruity" compounds resembling apple, pear, pineapple, banana, plum, or prune, among others.

After the introduction of hops into England from Flanders in the 15th century, "ale" referred to an unhopped fermented drink, "beer" being used to describe a brew with an infusion of hops.

Real ale is the term coined by the Campaign for Real Ale (CAMRA) in 1973 for "beer brewed from traditional ingredients, matured by secondary fermentation in the container from which it is dispensed, and served without the use of extraneous carbon dioxide". It is applied to bottle conditioned and cask conditioned beers.

Pale ale is a beer which uses a top-fermenting yeast, and predominantly pale malt. It is one of the world's major beer styles and includes India pale ale (IPA).

Mild ale has a predominantly malty palate. It is usually dark coloured with an abv of 3% to 3.6%, although there are lighter hued milds as well as stronger examples reaching 6% abv and higher.

Wheat beer is brewed with a large proportion of wheat although it often also contains a significant proportion of malted barley. Wheat beers are usually top-fermented. The flavour of wheat beers varies considerably, depending upon the specific style.

Stout is a dark beer made using roasted barley, and typically brewed with slow fermenting yeast. There are a number of variations including dry stout (such as Guinness), sweet stout, and Imperial (or Russian) stout. Stout was originally the strongest variety of porter, a dark brown beer popular with the street and river porters of eighteenth century London.

Bottom-fermented beers
Lager is cool fermented beer. Pale lagers are the most commonly consumed beers in the world. Many are of the "pilsner" type. The name "lager" comes from the German "lagern" for "to store", as brewers around Bavaria stored beer in cool cellars and caves during the warm summer months. These brewers noticed that the beers continued to ferment, and to also clear of sediment, when stored in cool conditions.

Lager yeast is a cool bottom-fermenting yeast (Saccharomyces pastorianus) and typically undergoes primary fermentation at 7 – (the fermentation phase), and then is given a long secondary fermentation at 0 – (the lagering phase). During the secondary stage, the lager clears and mellows. The cooler conditions also inhibit the natural production of esters and other byproducts, resulting in a "cleaner"-tasting beer.

With improved modern yeast strains, most lager breweries use only short periods of cold storage, typically 1–3 weeks.

Other types of beer
Lambic, a beer of Belgium, is naturally fermented using wild yeasts, rather than cultivated. Many of these are not strains of brewer's yeast (Saccharomyces cerevisiae) and may have significant differences in aroma and sourness. Yeast varieties such as Brettanomyces bruxellensis and Brettanomyces lambicus are common in lambics. In addition, other organisms such as Lactobacillus bacteria produce acids which contribute to the sourness.

Measurement
Beer is measured and assessed by colour, by strength and by bitterness. The perceived bitterness is measured by the International Bitterness Units scale (IBU), defined in co-operation between the American Society of Brewing Chemists and the European Brewery Convention. The international scale was a development of the European Bitterness Units scale, often abbreviated as EBU, and the bitterness values should be identical.

Colour

Beer colour is determined by the malt. The most common colour is a pale amber produced from using pale malts. Pale lager and pale ale are terms used for beers made from malt dried and roasted with the fuel coke. Coke was first used for roasting malt in 1642, but it was not until around 1703 that the term pale ale was used.

In terms of sales volume, most of today's beer is based on the pale lager brewed in 1842 in the town of Pilsen in the present-day Czech Republic. The modern pale lager is light in colour due to use of coke for kilning, which gives off heat with little smoke.

Dark beers are usually brewed from a pale malt or lager malt base with a small proportion of darker malt added to achieve the desired shade. Other colourants—such as caramel—are also widely used to darken beers. Very dark beers, such as stout, use dark or patent malts that have been roasted longer. Some have roasted unmalted barley.

Strength
Beer ranges from less than 3% alcohol by volume (abv) to around 14% abv, though this strength can be increased to around 20% by re-pitching with champagne yeast, and to 55% abv by the freeze-distilling process. The alcohol content of beer varies by local practice or beer style. The pale lagers that most consumers are familiar with fall in the range of 4–6%, with a typical abv of 5%. The customary strength of British ales is quite low, with many session beers being around 4% abv. In Belgium, some beers, such as table beer are of such low alcohol content (1%–4%) that they are served instead of soft drinks in some schools. The weakest beers are dealcoholized beers, which typically have less than 0.05% alcohol (also called "near beer") and light beers, which usually have 4% alcohol.

The alcohol in beer comes primarily from the metabolism of sugars that are produced during fermentation. The quantity of fermentable sugars in the wort and the variety of yeast used to ferment the wort are the primary factors that determine the amount of alcohol in the final beer. Additional fermentable sugars are sometimes added to increase alcohol content, and enzymes are often added to the wort for certain styles of beer (primarily "light" beers) to convert more complex carbohydrates (starches) to fermentable sugars. Alcohol is a by-product of yeast metabolism and is toxic to the yeast in higher concentrations; typical brewing yeast cannot survive at alcohol concentrations above 12% by volume. Low temperatures and too little fermentation time decreases the effectiveness of yeasts and consequently decreases the alcohol content.

The strength of beers has climbed during the later years of the 20th century. Vetter 33, a 10.5% abv (33 degrees Plato, hence Vetter "33") doppelbock, was listed in the 1994 Guinness Book of World Records as the strongest beer at that time, though Samichlaus, by the Swiss brewer Hürlimann, had also been listed by the Guinness Book of World Records as the strongest at 14% abv. Since then, some brewers have used champagne yeasts to increase the alcohol content of their beers. Samuel Adams reached 20% abv with Millennium, and then surpassed that amount to 25.6% abv with Utopias. The strongest beer brewed in Britain was Baz's Super Brew by Parish Brewery, a 23% abv beer. In September 2011, the Scottish brewery BrewDog produced Ghost Deer, which, at 28%, they claim to be the world's strongest beer produced by fermentation alone.

The product claimed to be the strongest beer made is Schorschbräu's 2011 Schorschbock 57 with 57,5%. It was preceded by The End of History, a 55% Belgian ale, made by BrewDog in 2010. The same company had previously made Sink The Bismarck!, a 41% abv IPA, and Tactical Nuclear Penguin, a 32% abv Imperial stout. Each of these beers are made using the eisbock method of fractional freezing, in which a strong ale is partially frozen and the ice is repeatedly removed, until the desired strength is reached, a process that may class the product as spirits rather than beer. The German brewery Schorschbräu's Schorschbock, a 31% abv eisbock,  and Hair of the Dog's Dave, a 29% abv barley wine made in 1994, used the same fractional freezing method. A 60% abv blend of beer with whiskey was jokingly claimed as the strongest beer by a Dutch brewery in July 2010.

Draught

Draught (also spelled "draft") beer from a pressurised keg using a lever-style dispenser and a spout is the most common method of dispensing in bars around the world. A metal keg is pressurised with carbon dioxide (CO2) gas which drives the beer to the dispensing tap or faucet. Some beers may be served with a nitrogen/carbon dioxide mixture. Nitrogen produces fine bubbles, resulting in a dense head and a creamy mouthfeel. Some types of beer can also be found in smaller, disposable kegs called beer balls. In traditional pubs, the pull levers for major beer brands may include the beer's logo and trademark.

In the 1980s, Guinness introduced the beer widget, a nitrogen-pressurised ball inside a can which creates a dense, tight head, similar to beer served from a nitrogen system. The words draft and draught can be used as marketing terms to describe canned or bottled beers containing a beer widget, or which are cold-filtered rather than pasteurised.

Cask-conditioned ales (or cask ales) are unfiltered and unpasteurised beers. These beers are termed "real ale" by the CAMRA organisation. Typically, when a cask arrives in a pub, it is placed horizontally on a frame called a "stillage" which is designed to hold it steady and at the right angle, and then allowed to cool to cellar temperature (typically between 11 –), before being tapped and vented—a tap is driven through a (usually rubber) bung at the bottom of one end, and a hard spile or other implement is used to open a hole in the side of the cask, which is now uppermost. The act of stillaging and then venting a beer in this manner typically disturbs all the sediment, so it must be left for a suitable period to "drop" (clear) again, as well as to fully condition—this period can take anywhere from several hours to several days. At this point the beer is ready to sell, either being pulled through a beer line with a hand pump, or simply being "gravity-fed" directly into the glass.

Draught beer's environmental impact can be 68% lower than bottled beer due to packaging differences. A life cycle study of one beer brand, including grain production, brewing, bottling, distribution and waste management, shows that the CO2 emissions from a 6-pack of micro-brew beer is about 3 kilograms (6.6 pounds). The loss of natural habitat potential from the 6-pack of micro-brew beer is estimated to be 2.5 square metres (26 square feet). Downstream emissions from distribution, retail, storage and disposal of waste can be over 45% of a bottled micro-brew beer's CO2 emissions. Where legal, the use of a refillable jug, reusable bottle or other reusable containers to transport draught beer from a store or a bar, rather than buying pre-bottled beer, can reduce the environmental impact of beer consumption.

Packaging

Most beers are cleared of yeast by filtering when packaged in bottles and cans. However, bottle conditioned beers retain some yeast—either by being unfiltered, or by being filtered and then reseeded with fresh yeast. It is usually recommended that the beer be poured slowly, leaving any yeast sediment at the bottom of the bottle. However, some drinkers prefer to pour in the yeast; this practice is customary with wheat beers. Typically, when serving a hefeweizen wheat beer, 90% of the contents are poured, and the remainder is swirled to suspend the sediment before pouring it into the glass. Alternatively, the bottle may be inverted prior to opening. Glass bottles are always used for bottle conditioned beers.

Many beers are sold in cans, though there is considerable variation in the proportion between different countries. In Sweden in 2001, 63.9% of beer was sold in cans. People either drink from the can or pour the beer into a glass. A technology developed by Crown Holdings for the 2010 FIFA World Cup is the 'full aperture' can, so named because the entire lid is removed during the opening process, turning the can into a drinking cup. Cans protect the beer from light (thereby preventing "skunked" beer) and have a seal less prone to leaking over time than bottles. Cans were initially viewed as a technological breakthrough for maintaining the quality of a beer, then became commonly associated with less expensive, mass-produced beers, even though the quality of storage in cans is much like bottles. Plastic (PET) bottles are used by some breweries.

Temperature
The temperature of a beer has an influence on a drinker's experience; warmer temperatures reveal the range of flavours in a beer but cooler temperatures are more refreshing. Most drinkers prefer pale lager to be served chilled, a low- or medium-strength pale ale to be served cool, while a strong barley wine or imperial stout to be served at room temperature.

Beer writer Michael Jackson proposed a five-level scale for serving temperatures: well chilled (7 °C) for "light" beers (pale lagers); chilled (8 °C) for Berliner Weisse and other wheat beers; lightly chilled (9 °C) for all dark lagers, altbier and German wheat beers; cellar temperature (13 °C) for regular British ale, stout and most Belgian specialities; and room temperature (15.5 °C) for strong dark ales (especially trappist beer) and barley wine.

Drinking chilled beer began with the development of artificial refrigeration and by the 1870s, was spread in those countries that concentrated on brewing pale lager. Chilling beer makes it more refreshing, though below 15.5 °C (60 °F) the chilling starts to reduce taste awareness and reduces it significantly below 10 °C. Beer served unchilled—either cool or at room temperature—reveal more of their flavours. Cask Marque, a non-profit UK beer organisation, has set a temperature standard range of 12°–14 °C (53°–57 °F) for cask ales to be served.

Vessels
Beer is consumed out of a variety of vessels, such as a glass, a beer stein, a mug, a pewter tankard, a beer bottle or a can; or at music festivals and some bars and nightclubs, from a plastic cup. The shape of the glass from which beer is consumed can influence the perception of the beer and can define and accent the character of the style. Breweries offer branded glassware intended only for their own beers as a marketing promotion, as this increases sales of their product.

The pouring process has an influence on a beer's presentation. The rate of flow from the tap or other serving vessel, tilt of the glass, and position of the pour (in the centre or down the side) into the glass all influence the result, such as the size and longevity of the head, lacing (the pattern left by the head as it moves down the glass as the beer is drunk), and the release of carbonation. A beer tower is a beer dispensing device, usually found in bars and pubs, that consists of a cylinder attached to a beer cooling device at the bottom. Beer is dispensed from the beer tower into a drinking vessel.

Chemistry
Beer contains the phenolic acids 4-hydroxyphenylacetic acid, vanillic acid, caffeic acid, syringic acid, p-coumaric acid, ferulic acid, and sinapic acid. Alkaline hydrolysis experiments show that most of the phenolic acids are present as bound forms and only a small portion can be detected as free compounds. Hops, and beer made with it, contain 8-prenylnaringenin which is a potent phytoestrogen. Hop also contains myrcene, humulene, xanthohumol, isoxanthohumol, myrcenol, linalool, tannins, and resin. The alcohol 2M2B is a component of hops brewing.

Barley, in the form of malt, brings the condensed tannins prodelphinidins B3, B9 and C2 into beer. Tryptophol, tyrosol, and phenylethanol are aromatic higher alcohols found in beer as secondary products of alcoholic fermentation (products also known as congeners) by Saccharomyces cerevisiae.

Nutritional information
Beers vary in their nutritional content. The ingredients used to make beer, including the yeast, provide a rich source of nutrients; therefore beer may contain nutrients including magnesium, selenium, potassium, phosphorus, biotin, chromium and B vitamins. Beer is sometimes referred to as "liquid bread", though beer is not a meal in itself.

Society and culture

In many societies, beer is the most popular alcoholic drink. Various social traditions and activities are associated with beer drinking, such as playing cards, darts, or other pub games; attending beer festivals; engaging in zythology (the study of beer); visiting a series of pubs in one evening; visiting breweries; beer-oriented tourism; or rating beer. Drinking games, such as beer pong, are also popular. Even having a "shower beer" has developed a following. A relatively new profession is that of the beer sommelier, who informs restaurant patrons about beers and food pairings. Some breweries have developed beers to pair with food. Wine writer Malcolm Gluck disputed the need to pair beer with food, while beer writers Roger Protz and Melissa Cole contested that claim.

Beer is considered to be a social lubricant in many societies and is consumed in countries all over the world. There are breweries in Middle Eastern countries such as Syria, and in some African countries. Sales of beer are four times those of wine, which is the second most popular alcoholic drink.

A study published in the Neuropsychopharmacology journal in 2013 revealed the finding that the flavour of beer alone could provoke dopamine activity in the brain of the male participants, who wanted to drink more as a result. The 49 men in the study were subject to positron emission tomography scans, while a computer-controlled device sprayed minute amounts of beer, water and a sports drink onto their tongues. Compared with the taste of the sports drink, the taste of beer significantly increased the participants desire to drink. Test results indicated that the flavour of the beer triggered a dopamine release, even though alcohol content in the spray was insufficient for the purpose of becoming intoxicated.

Related drinks
Around the world, there are many traditional and ancient starch-based drinks classed as beer. In Africa, there are various ethnic beers made from sorghum or millet, such as Oshikundu in Namibia and Tella in Ethiopia. Kyrgyzstan also has a beer made from millet; it is a low alcohol, somewhat porridge-like drink called "Bozo". Bhutan, Nepal, Tibet and Sikkim also use millet in Chhaang, a popular semi-fermented rice/millet drink in the eastern Himalayas. Further east in China are found Huangjiu and Choujiu—traditional rice-based drinks related to beer.

The Andes in South America has Chicha, made from germinated maize (corn); while the indigenous peoples in Brazil have Cauim, a traditional drink made since pre-Columbian times by chewing manioc so that an enzyme (amylase) present in human saliva can break down the starch into fermentable sugars; this is similar to Masato in Peru.

Some beers which are made from bread, which is linked to the earliest forms of beer, are Sahti in Finland, Kvass in Russia and Ukraine, and Bouza in Sudan. 4000 years ago fermented bread was used in Mesopotamia. Food waste activists got inspired by these ancient recipes and use leftover bread to replace a third of the malted barley that would otherwise be used for brewing their craft ale.

Health effects
A 2016 systematic review and meta-analysis found that moderate ethanol consumption brought no mortality benefit compared with lifetime abstention from ethanol consumption. Some studies have concluded that drinking small quantities of alcohol (less than one drink in women and two in men, per day) is associated with a decreased risk of heart disease, stroke, diabetes mellitus, and early death. Some of these studies combined former ethanol drinkers and lifelong abstainers into a single group of nondrinkers, which hides the health benefits of lifelong abstention from ethanol. The long-term health effects of continuous, moderate or heavy alcohol consumption include the risk of developing alcoholism and alcoholic liver disease. Alcoholism, also known as "alcohol use disorder", is a broad term for any drinking of alcohol that results in problems. It was previously divided into two types: alcohol abuse and alcohol dependence. In a medical context, alcoholism is said to exist when two or more of the following conditions are present: a person drinks large amounts over a long time period, has difficulty cutting down, acquiring and drinking alcohol takes up a great deal of time, alcohol is strongly desired, usage results in not fulfilling responsibilities, usage results in social problems, usage results in health problems, usage results in risky situations, withdrawal occurs when stopping, and alcohol tolerance has occurred with use. Alcoholism reduces a person's life expectancy by around ten years and alcohol use is the third leading cause of early death in the United States. No professional medical association recommends that people who are nondrinkers should start drinking alcoholic beverages. In the United States, a total of 3.3 million deaths per year (5.9% of all deaths) are believed to be due to alcohol.

It is considered that overeating and lack of muscle tone is the main cause of a beer belly, rather than beer consumption. A 2004 study, however, found a link between binge drinking and a beer belly. But with most overconsumption, it is more a problem of improper exercise and overconsumption of carbohydrates than the product itself. Several diet books quote beer as having an undesirably high glycemic index of 110, the same as maltose; however, the maltose in beer undergoes metabolism by yeast during fermentation so that beer consists mostly of water, hop oils and only trace amounts of sugars, including maltose.

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Bit

The bit is the most basic unit of information in computing and digital communication. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented as either "1" or "0", but other representations such as true/false, yes/no, on/off, or +/− are also widely used.

The relation between these values and the physical states of the underlying storage or device is a matter of convention, and different assignments may be used even within the same device or program. It may be physically implemented with a two-state device.

A contiguous group of binary digits is commonly called a bit string, a bit vector, or a single-dimensional (or multi-dimensional) bit array. A group of eight bits is called one byte, but historically the size of the byte is not strictly defined. Frequently, half, full, double and quadruple words consist of a number of bytes which is a low power of two. A string of four bits is usually a nibble.

In information theory, one bit is the information entropy of a random binary variable that is 0 or 1 with equal probability, or the information that is gained when the value of such a variable becomes known. As a unit of information, the bit is also known as a shannon, named after Claude E. Shannon.

The symbol for the binary digit is either "bit", per the IEC 80000-13:2008 standard, or the lowercase character "b", per the IEEE 1541-2002 standard. Use of the latter may create confusion with the capital "B" which is the international standard symbol for the byte.

History
The encoding of data by discrete bits was used in the punched cards invented by Basile Bouchon and Jean-Baptiste Falcon (1732), developed by Joseph Marie Jacquard (1804), and later adopted by Semyon Korsakov, Charles Babbage, Herman Hollerith, and early computer manufacturers like IBM. A variant of that idea was the perforated paper tape. In all those systems, the medium (card or tape) conceptually carried an array of hole positions; each position could be either punched through or not, thus carrying one bit of information. The encoding of text by bits was also used in Morse code (1844) and early digital communications machines such as teletypes and stock ticker machines (1870).

Ralph Hartley suggested the use of a logarithmic measure of information in 1928. Claude E. Shannon first used the word "bit" in his seminal 1948 paper "A Mathematical Theory of Communication". He attributed its origin to John W. Tukey, who had written a Bell Labs memo on 9 January 1947 in which he contracted "binary information digit" to simply "bit".

Physical representation
A bit can be stored by a digital device or other physical system that exists in either of two possible distinct states. These may be the two stable states of a flip-flop, two positions of an electrical switch, two distinct voltage or current levels allowed by a circuit, two distinct levels of light intensity, two directions of magnetization or polarization, the orientation of reversible double stranded DNA, etc.

Bits can be implemented in several forms. In most modern computing devices, a bit is usually represented by an electrical voltage or current pulse, or by the electrical state of a flip-flop circuit.

For devices using positive logic, a digit value of 1 (or a logical value of true) is represented by a more positive voltage relative to the representation of 0. Different logic families require different voltages, and variations are allowed to account for component aging and noise immunity. For example, in transistor–transistor logic (TTL) and compatible circuits, digit values 0 and 1 at the output of a device are represented by no higher than 0.4 volts and no lower than 2.6 volts, respectively; while TTL inputs are specified to recognize 0.8 volts or below as 0 and 2.2 volts or above as 1.

Transmission and processing
Bits are transmitted one at a time in serial transmission, and by a multiple number of bits in parallel transmission. A bitwise operation optionally processes bits one at a time. Data transfer rates are usually measured in decimal SI multiples of the unit bit per second (bit/s), such as kbit/s.

Storage
In the earliest non-electronic information processing devices, such as Jacquard's loom or Babbage's Analytical Engine, a bit was often stored as the position of a mechanical lever or gear, or the presence or absence of a hole at a specific point of a paper card or tape. The first electrical devices for discrete logic (such as elevator and traffic light control circuits, telephone switches, and Konrad Zuse's computer) represented bits as the states of electrical relays which could be either "open" or "closed". When relays were replaced by vacuum tubes, starting in the 1940s, computer builders experimented with a variety of storage methods, such as pressure pulses traveling down a mercury delay line, charges stored on the inside surface of a cathode-ray tube, or opaque spots printed on glass discs by photolithographic techniques.

In the 1950s and 1960s, these methods were largely supplanted by magnetic storage devices such as magnetic-core memory, magnetic tapes, drums, and disks, where a bit was represented by the polarity of magnetization of a certain area of a ferromagnetic film, or by a change in polarity from one direction to the other. The same principle was later used in the magnetic bubble memory developed in the 1980s, and is still found in various magnetic strip items such as metro tickets and some credit cards.

In modern semiconductor memory, such as dynamic random-access memory, the two values of a bit may be represented by two levels of electric charge stored in a capacitor. In certain types of programmable logic arrays and read-only memory, a bit may be represented by the presence or absence of a conducting path at a certain point of a circuit. In optical discs, a bit is encoded as the presence or absence of a microscopic pit on a reflective surface. In one-dimensional bar codes, bits are encoded as the thickness of alternating black and white lines.

Unit and symbol
The bit is not defined in the International System of Units (SI). However, the International Electrotechnical Commission issued standard IEC 60027, which specifies that the symbol for binary digit should be 'bit', and this should be used in all multiples, such as 'kbit', for kilobit. However, the lower-case letter 'b' is widely used as well and was recommended by the IEEE 1541 Standard (2002). In contrast, the upper case letter 'B' is the standard and customary symbol for byte.

Multiple bits
Multiple bits may be expressed and represented in several ways. For convenience of representing commonly reoccurring groups of bits in information technology, several units of information have traditionally been used. The most common is the unit byte, coined by Werner Buchholz in June 1956, which historically was used to represent the group of bits used to encode a single character of text (until UTF-8 multibyte encoding took over) in a computer    and for this reason it was used as the basic addressable element in many computer architectures. The trend in hardware design converged on the most common implementation of using eight bits per byte, as it is widely used today. However, because of the ambiguity of relying on the underlying hardware design, the unit octet was defined to explicitly denote a sequence of eight bits.

Computers usually manipulate bits in groups of a fixed size, conventionally named "words". Like the byte, the number of bits in a word also varies with the hardware design, and is typically between 8 and 80 bits, or even more in some specialized computers. In the 21st century, retail personal or server computers have a word size of 32 or 64 bits.

The International System of Units defines a series of decimal prefixes for multiples of standardized units which are commonly also used with the bit and the byte. The prefixes kilo (103) through yotta (1024) increment by multiples of one thousand, and the corresponding units are the kilobit (kbit) through the yottabit (Ybit).

Information capacity and information compression
When the information capacity of a storage system or a communication channel is presented in bits or bits per second, this often refers to binary digits, which is a computer hardware capacity to store binary data (0 or 1, up or down, current or not, etc.). Information capacity of a storage system is only an upper bound to the quantity of information stored therein. If the two possible values of one bit of storage are not equally likely, that bit of storage contains less than one bit of information. If the value is completely predictable, then the reading of that value provides no information at all (zero entropic bits, because no resolution of uncertainty occurs and therefore no information is available). If a computer file that uses n bits of storage contains only m < n bits of information, then that information can in principle be encoded in about m bits, at least on the average. This principle is the basis of data compression technology. Using an analogy, the hardware binary digits refer to the amount of storage space available (like the number of buckets available to store things), and the information content the filling, which comes in different levels of granularity (fine or coarse, that is, compressed or uncompressed information). When the granularity is finer—when information is more compressed—the same bucket can hold more.

For example, it is estimated that the combined technological capacity of the world to store information provides 1,300 exabytes of hardware digits. However, when this storage space is filled and the corresponding content is optimally compressed, this only represents 295 exabytes of information. When optimally compressed, the resulting carrying capacity approaches Shannon information or information entropy.

Bit-based computing
Certain bitwise computer processor instructions (such as bit set) operate at the level of manipulating bits rather than manipulating data interpreted as an aggregate of bits.

In the 1980s, when bitmapped computer displays became popular, some computers provided specialized bit block transfer instructions to set or copy the bits that corresponded to a given rectangular area on the screen.

In most computers and programming languages, when a bit within a group of bits, such as a byte or word, is referred to, it is usually specified by a number from 0 upwards corresponding to its position within the byte or word. However, 0 can refer to either the most or least significant bit depending on the context.

Other information units
Similar to torque and energy in physics; information-theoretic information and data storage size have the same dimensionality of units of measurement, but there is in general no meaning to adding, subtracting or otherwise combining the units mathematically, although one may act as a bound on the other.

Units of information used in information theory include the shannon (Sh), the natural unit of information (nat) and the hartley (Hart). One shannon is the maximum amount of information needed to specify the state of one bit of storage. These are related by 1 Sh ≈ 0.693 nat ≈ 0.301 Hart.

Some authors also define a binit as an arbitrary information unit equivalent to some fixed but unspecified number of bits.

title: Bit


text:
Byte

The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures. To disambiguate arbitrarily sized bytes from the common 8-bit definition, network protocol documents such as the Internet Protocol refer to an 8-bit byte as an octet. Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the bit endianness.

The size of the byte has historically been hardware-dependent and no definitive standards existed that mandated the size. Sizes from 1 to 48 bits have been used. The six-bit character code was an often-used implementation in early encoding systems, and computers using six-bit and nine-bit bytes were common in the 1960s. These systems often had memory words of 12, 18, 24, 30, 36, 48, or 60 bits, corresponding to 2, 3, 4, 5, 6, 8, or 10 six-bit bytes. In this era, bit groupings in the instruction stream were often referred to as syllables or slab, before the term byte became common.

The modern de facto standard of eight bits, as documented in ISO/IEC 2382-1:1993, is a convenient power of two permitting the binary-encoded values 0 through 255 for one byte, as 2 to the power of 8 is 256. The international standard IEC 80000-13 codified this common meaning. Many types of applications use information representable in eight or fewer bits and processor designers commonly optimize for this usage. The popularity of major commercial computing architectures has aided in the ubiquitous acceptance of the 8-bit byte. Modern architectures typically use 32- or 64-bit words, built of four or eight bytes, respectively.

The unit symbol for the byte was designated as the upper-case letter B by the International Electrotechnical Commission (IEC) and Institute of Electrical and Electronics Engineers (IEEE). Internationally, the unit octet, symbol o, explicitly defines a sequence of eight bits, eliminating the potential ambiguity of the term "byte".

Etymology and history
The term byte was coined by Werner Buchholz in June 1956,   during the early design phase for the IBM Stretch      computer, which had addressing to the bit and variable field length (VFL) instructions with a byte size encoded in the instruction. It is a deliberate respelling of bite to avoid accidental mutation to bit.

Another origin of byte for bit groups smaller than a computer's word size, and in particular groups of four bits, is on record by Louis G. Dooley, who claimed he coined the term while working with Jules Schwartz and Dick Beeler on an air defense system called SAGE at MIT Lincoln Laboratory in 1956 or 1957, which was jointly developed by Rand, MIT, and IBM. Later on, Schwartz's language JOVIAL actually used the term, but the author recalled vaguely that it was derived from AN/FSQ-31.

Early computers used a variety of four-bit binary-coded decimal (BCD) representations and the six-bit codes for printable graphic patterns common in the U.S. Army (FIELDATA) and Navy. These representations included alphanumeric characters and special graphical symbols. These sets were expanded in 1963 to seven bits of coding, called the American Standard Code for Information Interchange (ASCII) as the Federal Information Processing Standard, which replaced the incompatible teleprinter codes in use by different branches of the U.S. government and universities during the 1960s. ASCII included the distinction of upper- and lowercase alphabets and a set of control characters to facilitate the transmission of written language as well as printing device functions, such as page advance and line feed, and the physical or logical control of data flow over the transmission media. During the early 1960s, while also active in ASCII standardization, IBM simultaneously introduced in its product line of System/360 the eight-bit Extended Binary Coded Decimal Interchange Code (EBCDIC), an expansion of their six-bit binary-coded decimal (BCDIC) representations used in earlier card punches. The prominence of the System/360 led to the ubiquitous adoption of the eight-bit storage size,  while in detail the EBCDIC and ASCII encoding schemes are different.

In the early 1960s, AT&T introduced digital telephony on long-distance trunk lines. These used the eight-bit μ-law encoding. This large investment promised to reduce transmission costs for eight-bit data.

In Volume 1 of The Art of Computer Programming (first published in 1968), Donald Knuth uses byte in his hypothetical MIX computer to denote a unit which "contains an unspecified amount of information ... capable of holding at least 64 distinct values ... at most 100 distinct values. On a binary computer a byte must therefore be composed of six bits". He notes that "Since 1975 or so, the word byte has come to mean a sequence of precisely eight binary digits...When we speak of bytes in connection with MIX we shall confine ourselves to the former sense of the word, harking back to the days when bytes were not yet standardized."

The development of eight-bit microprocessors in the 1970s popularized this storage size. Microprocessors such as the Intel 8080, the direct predecessor of the 8086, could also perform a small number of operations on the four-bit pairs in a byte, such as the decimal-add-adjust (DAA) instruction. A four-bit quantity is often called a nibble, also nybble, which is conveniently represented by a single hexadecimal digit.

The term octet is used to unambiguously specify a size of eight bits. It is used extensively in protocol definitions.

Historically, the term octad or octade was used to denote eight bits as well at least in Western Europe; however, this usage is no longer common. The exact origin of the term is unclear, but it can be found in British, Dutch, and German sources of the 1960s and 1970s, and throughout the documentation of Philips mainframe computers.

Unit symbol
The unit symbol for the byte is specified in IEC 80000-13, IEEE 1541 and the Metric Interchange Format as the upper-case character B.

In the International System of Quantities (ISQ), B is also the symbol of the bel, a unit of logarithmic power ratio named after Alexander Graham Bell, creating a conflict with the IEC specification. However, little danger of confusion exists, because the bel is a rarely used unit. It is used primarily in its decadic fraction, the decibel (dB), for signal strength and sound pressure level measurements, while a unit for one-tenth of a byte, the decibyte, and other fractions, are only used in derived units, such as transmission rates.

The lowercase letter o for octet is defined as the symbol for octet in IEC 80000-13 and is commonly used in languages such as French and Romanian, and is also combined with metric prefixes for multiples, for example ko and Mo.

Multiple-byte units
More than one system exists to define unit multiples based on the byte. Some systems are based on powers of 10, following the International System of Units (SI), which defines for example the prefix kilo as 1000 (103); other systems are based on powers of 2. Nomenclature for these systems has led to confusion. Systems based on powers of 10 use standard SI prefixes (kilo, mega, giga, ...) and their corresponding symbols (k, M, G, ...). Systems based on powers of 2, however, might use binary prefixes (kibi, mebi, gibi, ...) and their corresponding symbols (Ki, Mi, Gi, ...) or they might use the prefixes K, M, and G, creating ambiguity when the prefixes M or G are used.

While the difference between the decimal and binary interpretations is relatively small for the kilobyte (about 2% smaller than the kibibyte), the systems deviate increasingly as units grow larger (the relative deviation grows by 2.4% for each three orders of magnitude). For example, a power-of-10-based terabyte is about 9% smaller than power-of-2-based tebibyte.

Units based on powers of 10
Definition of prefixes using powers of 10—in which 1 kilobyte (symbol kB) is defined to equal 1,000 bytes—is recommended by the International Electrotechnical Commission (IEC). The IEC standard defines eight such multiples, up to 1 yottabyte (YB), equal to 10008 bytes. The additional prefixes ronna- for 10009 and quetta- for 100010 were adopted by the International Bureau of Weights and Measures (BIPM) in 2022.

This definition is most commonly used for data-rate units in computer networks, internal bus, hard drive and flash media transfer speeds, and for the capacities of most storage media, particularly hard drives, flash-based storage, and DVDs. Operating systems that use this definition include macOS, iOS, Ubuntu, and Debian. It is also consistent with the other uses of the SI prefixes in computing, such as CPU clock speeds or measures of performance.

Units based on powers of 2
A system of units based on powers of 2 in which 1 kibibyte (KiB) is equal to 1,024 (i.e., 210) bytes is defined by international standard IEC 80000-13 and is supported by national and international standards bodies (BIPM, IEC, NIST). The IEC standard defines eight such multiples, up to 1 yobibyte (YiB), equal to 10248 bytes. The natural binary counterparts to ronna- and quetta- were given in a consultation paper of the International Committee for Weights and Measures' Consultative Committee for Units (CCU) as robi- (Ri, 10249) and quebi- (Qi, 102410), but have not yet been adopted by the IEC and ISO.

An alternative system of nomenclature for the same units (referred to here as the customary convention), in which 1 kilobyte (KB) is equal to 1,024 bytes,  1 megabyte (MB) is equal to 10242 bytes and  1 gigabyte (GB) is equal to 10243 bytes is mentioned by a 1990s JEDEC standard. Only the first three multiples (up to GB) are mentioned by the JEDEC standard, which makes no mention of TB and larger. While confusing and incorrect, the customary convention is used by the Microsoft Windows operating system and random-access memory capacity, such as main memory and CPU cache size, and in marketing and billing by telecommunication companies, such as Vodafone, AT&T, Orange and Telstra.

For storage capacity, the customary convention was used by macOS and iOS through Mac OS X 10.6 Snow Leopard and iOS 10, after which they switched to units based on powers of 10.

Parochial units
Various computer vendors have coined terms for data of various sizes, sometimes with different sizes for the same term even within a single vendor. These terms include double word, half word, long word, quad word, slab, superword and syllable. There are also informal terms. e.g., half byte and nybble for 4 bits, octal K for.

History of the conflicting definitions

Contemporary computer memory has a binary architecture making a definition of memory units based on powers of 2 most practical. The use of the metric prefix kilo for binary multiples arose as a convenience, because 1,024 is approximately 1,000. This definition was popular in early decades of personal computing, with products like the Tandon 51⁄4-inch DD floppy format (holding 368,640 bytes) being advertised as "360 KB", following the 1,024-byte convention. It was not universal, however. The Shugart SA-400 51⁄4-inch floppy disk held 109,375 bytes unformatted, and was advertised as "110 Kbyte", using the 1000 convention. Likewise, the 8-inch DEC RX01 floppy (1975) held 256,256 bytes formatted, and was advertised as "256k". Some devices were advertised using a mixture of the two definitions: most notably, floppy disks advertised as "1.44 MB" have an actual capacity of 1,440 KiB, the equivalent of 1.47 MB or 1.41 MiB.

In 1995, the International Union of Pure and Applied Chemistry's (IUPAC) Interdivisional Committee on Nomenclature and Symbols attempted to resolve this ambiguity by proposing a set of binary prefixes for the powers of 1024, including kibi (kilobinary), mebi (megabinary), and gibi (gigabinary).

In December 1998, the IEC addressed such multiple usages and definitions by adopting the IUPAC's proposed prefixes (kibi, mebi, gibi, etc.) to unambiguously denote powers of 1024. Thus one kibibyte (1 KiB) is 10241 bytes = 1024 bytes, one mebibyte (1 MiB) is 10242  bytes = $1,048,576$ bytes, and so on.

In 1999, Donald Knuth suggested calling the kibibyte a "large kilobyte" (KKB).

Modern standard definitions
The IEC adopted the IUPAC proposal and published the standard in January 1999. The IEC prefixes are part of the International System of Quantities. The IEC further specified that the kilobyte should only be used to refer to 1,000 bytes.

Lawsuits over definition
Lawsuits arising from alleged consumer confusion over the binary and decimal definitions of multiples of the byte have generally ended in favor of the manufacturers, with courts holding that the legal definition of gigabyte or GB is 1 GB = 1,000,000,000 (109) bytes (the decimal definition), rather than the binary definition (230, i.e., 1,073,741,824). Specifically, the United States District Court for the Northern District of California held that "the U.S. Congress has deemed the decimal definition of gigabyte to be the 'preferred' one for the purposes of 'U.S. trade and commerce' [...] The California Legislature has likewise adopted the decimal system for all 'transactions in this state.

Earlier lawsuits had ended in settlement with no court ruling on the question, such as a lawsuit against drive manufacturer Western Digital. Western Digital settled the challenge and added explicit disclaimers to products that the usable capacity may differ from the advertised capacity. Seagate was sued on similar grounds and also settled.

Common uses
Many programming languages define the data type byte.

The C and C++ programming languages define byte as an "addressable unit of data storage large enough to hold any member of the basic character set of the execution environment" (clause 3.6 of the C standard). The C standard requires that the integral data type unsigned char must hold at least 256 different values, and is represented by at least eight bits (clause 5.2.4.2.1). Various implementations of C and C++ reserve 8, 9, 16, 32, or 36 bits for the storage of a byte. In addition, the C and C++ standards require that there are no gaps between two bytes. This means every bit in memory is part of a byte.

Java's primitive data type byte is defined as eight bits. It is a signed data type, holding values from −128 to 127.

.NET programming languages, such as C#, define byte as an unsigned type, and the sbyte as a signed data type, holding values from 0 to 255, and −128 to 127, respectively.

In data transmission systems, the byte is used as a contiguous sequence of bits in a serial data stream, representing the smallest distinguished unit of data. For asynchronous communication a full transmission unit usually additionally includes a start bit, 1 or 2 stop bits, and possibly a parity bit, and thus its size may vary from seven to twelve bits for five to eight bits of actual data. For synchronous communication the error checking usually uses bytes at the end of a frame.

title: Byte