For other uses see Beer (disambiguation).
Beer is the world's oldest and most widely consumed alcoholic beverage and the third most popular drink overall after water and tea. It is produced by the brewing and fermentation of starches, mainly derived from cereal grains—the most common of which is malted barley, although wheat, maize (corn), and rice are widely used. Most beer is flavoured with hops, which add bitterness and act as a natural preservative, though other flavourings such as herbs or fruit may occasionally be included. Alcoholic beverages distilled after fermentation or fermented from non-starch sources such as grape juice (wine) or honey (mead) are not classified as beer.
Some of humanity's earliest known writings refer to the production and distribution of beer: the Code of Hammurabi included laws regulating beer and beer parlours, and "The Hymn to Ninkasi," a prayer to the Mesopotamian goddess of beer, served as both a prayer and as a method of remembering the recipe for beer in a culture with few literate people. Today, 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 basics of brewing beer are shared across national and cultural boundaries and are commonly categorized into two main types based on the type of yeast used during fermenting — the globally popular lagers, which is brewed with bottom-fermenting yeast, and the regionally distinct ales, brewed with top fermenting yeast. Ales are further categorised into other varieties such as pale ale, stout and brown ale. The strength of beer is usually around 4% to 6% alcohol by volume (abv.) though may range from less than 1% abv., to over 20% abv. in rare cases.
Beer forms part of the culture of various beer-drinking nations and has acquired various social traditions and associations, such as beer festivals and a rich pub culture involving activities such as pub crawling or pub games such as bar billiards.
See main article: History of beer. Beer is one of the world's oldest beverages, possibly dating back to 6000 BC, and is recorded in the written history of ancient Egypt and Mesopotamia. The earliest Sumerian writings contain references to a type of beer. A prayer to the goddess Ninkasi, known as "The Hymn to Ninkasi", serves as both a prayer as well as a method of remembering the recipe for beer in a culture with few literate people.
As almost any substance containing carbohydrates, mainly sugar or starch, can naturally undergo fermentation, it is likely that beer-like beverages were independently invented among various cultures throughout the world. The invention of bread and beer has been argued to be responsible for humanity's ability to develop technology and build civilization.   The earliest known chemical evidence of beer dates to circa 3500–3100 BC from the site of Godin Tepe in the Zagros Mountains of western Iran.
Beer was spread through Europe by Germanic and Celtic tribes as far back as 3000 BC, though 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. The early European beers might contain alongside the basic starch source: fruits, honey, numerous types of plants, spices and other substances such as narcotic drugs. 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.
Beer produced before the Industrial Revolution continued to be made and sold on a domestic scale, although by the 7th century AD, 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.
Today, 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. More than 133 billion liters (35 billion gallons) are sold per year (the equivalent of a cube 510 metres on a side), producing total global revenues of $294.5 billion (£147.7 billion) in 2006.
See main article: 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 in the home and has been for much of beer's history. A company which makes beer is called either a brewery or a brewing company. Beer made on a domestic scale for non-commercial reasons is classed as homebrewing regardless of where it is made, though most homebrewed beer is made in the home. Brewing beer is subject to legislation and taxation in developed countries, which from the late 19th century, largely restricted brewing to a commercial operation only. However, the UK government relaxed legislation in 1963, followed by Australia in 1972, and the USA in 1979, 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 beverage 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 now 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 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 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, 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 in order to extract bitterness, flavour and aroma from them. Hops may be added at more than one point during the boil. The longer the hops are boiled, the more bitterness they contribute, but less of the hop flavour and aroma remains in the beer.
After boiling, the hopped wort is now cooled, 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 which requires a week to months depending on the type of yeast and strength of the beer. In addition to producing alcohol, fine particulate matter suspended in the wort settles during fermentation. Once fermentation is complete, the yeast also settles, leaving the beer clear.
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, aluminum cans, or bottles for other sorts of beer.
The basic ingredients of beer are water; a starch source, such as malted barley, able to be fermented (converted into alcohol); 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 starch source, such as maize (corn), rice or sugar, often being termed an adjunct, especially when used as a lower-cost substitute for 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.
Beer is composed mostly of water. Regions have water with different mineral components; as a result, different regions were originally better suited to making certain types of beer, thus giving them a regional character. For example, Dublin has hard water well suited to making stout, such as Guinness; while Pilzen has soft water well suited to making 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.
See main article: Malt and Mash ingredients. The starch source 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 beer includes barley malt as the majority of the starch. This is because of its fibrous husk, which is not only important in the sparging stage of brewing (in which water is washed over the mashed barley grains to form the wort), but also as a rich source of amylase, a digestive enzyme which facilitates conversion of starch into sugars. Other malted and unmalted grains (including wheat, rice, oats, and rye, and less frequently, corn and sorghum) may be used. In recent years, a few 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.
See main article: Hops. 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 use of hops in beer was recorded by captive Jews in Babylon around 400 BC. Hops were used by monastery breweries, such as Corvey in Westphalia, Germany, from 822 AD,  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, Glechoma hederacea. 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 hops aids in "head retention",  the length of time that a foamy head created by carbonation will last. The acidity of hops is a preservative. 
See main article: Saccharomyces cerevisiae. Yeast is the microorganism that is responsible for fermentation in beer. Yeast metabolises the sugars extracted from grains, which produces 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 ale yeast (Saccharomyces cerevisiae) and lager yeast (Saccharomyces uvarum); their use distinguishes ale and lager. 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.
See main article: Finings. Some brewers add one or more clarifying agents 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 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 was clarified either with seaweed or with artificial agents.
See main article: Beer style. 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, the United Kingdom, Ireland, Poland, the Czech Republic, Denmark, the Netherlands and Austria—have local varieties of beer. In some countries, notably the USA, Canada and Australia, brewers have adapted European styles to such an extent that they have effectively created their own indigenous types.
Despite the regional variations, beer is categorised into two main types based on the type of yeast used during the brewing process — lagers, which is brewed with bottom fermenting yeast, and the more regionally distinct ales, brewed with top fermenting yeast. Ales are further categorised into other varieties such as pale ale, stout and brown ale.
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.
The most common method of categorising beer is by the behaviour of the yeast used in the fermentation process. In this method, beers using a fast-acting yeast which leaves behind residual sugars are termed "ales", while beers using a slower-acting yeast, fermented at lower temperatures, which removes most of the sugars, leaving a clean, dry beer, are termed "lagers". Differences between some ales and lagers can be difficult to categorise. Steam beer, Kölsch, Alt, and some modern British Golden Summer Beers use elements of both lager and ale production. Baltic Porter and Bière de Garde may be produced by either lager or ale methods or a combination of both. However, lager production results in a cleaner-tasting, drier and lighter beer than ale.
See main article: Ale. A modern ale is commonly defined by the strain of yeast used and the fermenting temperature. Ales are normally brewed with top-fermenting yeasts (most commonly Saccharomyces cerevisiae), though a number of British brewers, including Fullers and Weltons, use ale yeast strains that have less-pronounced top-fermentation characteristics. The important distinction for ales is that they are fermented at higher temperatures and thus ferment more quickly than lagers.
Ale is typically fermented at temperatures between 15 and 24°C (60 and 75°F). 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. Typically ales have a sweeter, fuller body than lagers.
Before the introduction of hops into England from the Netherlands in the 15th century, the name ale was exclusively applied to unhopped fermented beverages, the term beer being gradually introduced to describe a brew with an infusion of hops. This distinction no longer applies. The word ale may come from the Old English ealu, in turn from the Proto-Indo-European base *alut-, which holds connotations of "sorcery, magic, possession, intoxication".
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.
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.
Stout and porter are styles of dark ale made using roasted malts or roast barley, and brewed with top-fermenting ale yeast. There are a number of variations including Baltic porter, dry stout, and Imperial stout. The name Porter was first used in 1721 to describe a dark ale popular with street and river porters of London that had been made with roasted malts. This same beer later also became known as stout, though the word stout had been used as early as 1677. The history and development of stout and porter are intertwined.
See main article: Lager.
Lager is the English name for cool fermenting beers of Central European origin. Pale lagers are the most commonly consumed beers in the world. 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 7–12°C (45–55°F) (the fermentation phase), and then is given a long secondary fermentation at 0–4°C (32–40°F) (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.
Modern methods of producing lager were pioneered by Gabriel Sedlmayr the Younger, who perfected dark brown lagers at the Spaten Brewery in Bavaria, and Anton Dreher, who began brewing a lager, probably of amber-red colour, in Vienna in 1840–1841. With improved modern yeast strains, most lager breweries use only short periods of cold storage, typically 1–3 weeks.
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 with 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 with a noticeable carbonation (fizzy bubbles) and a typical alcohol by volume content of around 5%. The Pilsner Urquell, Bitburger, and Heineken brands of beer are typical examples of pale lager, as are the American brands Budweiser, Coors, and Miller.
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. 
Beer ranges from less than 3% alcohol by volume (abv) to almost 30% abv. 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. 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 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 byproduct of yeast metabolism and is toxic to the yeast; 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 sold in Britain was Baz's Super Brew by Parish Brewery, a 23% abv beer.  Delaware's Dogfish Head's World Wide Stout, a 21% abv stout was available from UK Safeways in 2003. The beer that is considered to be the strongest yet made is Hair of the Dog's Dave—a 29% abv barley wine made in 1994. The strength was achieved by using the eisbock method of freeze distilling - the brewery freeze distilled a 10% ale twice.
Around the world, there are a number of traditional and ancient starch-based beverages 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 beverages 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 beverage made since pre-Columbian times by chewing manioc so that enzymes present in human saliva can break down the starch into fermentable sugars; this is similar to Masato in Peru.
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. More than 133 billion liters (35 billion gallons) are sold per year—producing total global revenues of $294.5 billion (£147.7 billion) in 2006.
A microbrewery, or craft brewery, is a modern brewery which 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, though is usually around 15,000 barrels (18,000 hectolitres/ 475,000 US gallons) a year. A brewpub is a type of microbrewery that incorporates a pub or other eating establishment.
SABMiller became the largest brewing company in the world when it acquired Royal Grolsch, brewer of Dutch premium beer brand Grolsch. InBev was the second-largest beer-producing company in the world, and Anheuser-Busch held the third spot, but after the merger, between InBev and Anheuser-Busch, the new Anheuser-Busch InBev company is the largest brewer in the world. 
See main article: Draught beer and Cask ale. Draught beer from a pressurised keg 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 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 12-14°C/53-57°F), 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.
See main article: Beer bottle and Beverage can. 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, 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. 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.
The temperature of a beer has an influence on a drinker's experience; warmer temperatures reveal the range of flavours in a beer; however, 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/45 °F) for "light" beers (pale lagers); chilled (8 °C/47 °F) for Berliner Weisse and other wheat beers; lightly chilled (9 °C/48 °F) for all dark lagers, altbier and German wheat beers; cellar temperature (13 °C/55 °F) for regular British ale, stout and most Belgian specialities; and room temperature (15.5 °C/60 °F) for strong dark ales (especially trappist beer) and barley wine.
Drinking chilled beer is a social trend that began with the development of artificial refrigeration and by the 1870s, was spread in those countries that concentrated on brewing pale lager. Chilling below 15.5 °C/60 °F starts to reduce taste awareness and reduces it significantly below 10 °C/50 °F; while this is acceptable for beers without an appreciable aroma or taste profile, beers brewed with more than basic refreshment in mind reveal their flavours more when served unchilled—either cool or at room temperature. 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.
See main article: Beer glassware. 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. Some drinkers consider that the type of vessel influences their enjoyment of the beer. In Europe, particularly Belgium, breweries offer branded glassware intended only for their own beers.
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 end 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 turbulence of the beer and its release of carbonation.
Various social traditions and activities are associated with beer drinking, such as playing cards, darts, bags, or other pub games; attending beer festivals, or visiting a series of different pubs in one evening; joining an organisation such as CAMRA; or rating beer. Various drinking games, such as beer pong, flip cup and quarters are also popular.
See also: Beers of the world and Beer consumption by country. Beer is considered to be a social lubricant in many societies. Beer is consumed in countries all over the world. There are breweries in Middle Eastern countries such as Lebanon, Iraq and Syria as well as African countries (see African beer) and remote countries such as Mongolia. Sales of beer are four times that of wine, the second most popular alcoholic beverage.  In most societies, beer is the most popular alcoholic beverage.
The main active ingredient of beer is alcohol, and therefore, the health effects of alcohol apply to beer. The moderate consumption of alcohol, including beer, is associated with a decreased risk of cardiac disease, stroke and cognitive decline.    The long-term effects of alcohol abuse include the risk of developing alcoholism, alcoholic liver disease, and some forms of cancer.
Brewer's yeast is known to be a rich source of nutrients; therefore, as expected, beer can contain significant amounts of nutrients, including magnesium, selenium, potassium, phosphorus, biotin, and B vitamins. In fact, beer is sometimes referred to as "liquid bread". Some sources maintain that filtered beer loses much of its nutrition. 
A 2005 Japanese study found that low alcohol beer may possess strong anti-cancer properties. Another study found nonalcoholic beer to mirror the cardiovascular benefits associated with moderate consumption of alcoholic beverages. However, much research suggests that the primary health benefit from alcoholic beverages comes from the alcohol they contain.
It is considered that overeating and lack of muscle tone is the main cause of a beer belly, rather than beer consumption. A recent 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 the same glycemic index as maltose, a very high (and therefore undesirable) 110; however, the maltose undergoes metabolism by yeast during fermentation so that beer consists mostly of water, hop oils and only trace amounts of sugars, including maltose.
Draught beer's environmental impact can be 68% lower than bottled beer due to packaging differences.  Home brewing can reduce the environmental impact of beer via less packaging and transportation.
A life cycle study of one beer brand shows that the CO2 emissions from a 6-pack of micro-brew beer is about 3 kilograms (6.6 pounds) -- including grain production, brewing, bottling, distribution and waste management. The loss of natural habitat potential from the 6-pack of micro-brew beer is estimated to be 2.5 square meters (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.
The use of a refillable jug, reusable bottle or other reusable containers to transport draught beer from a store or a bar (where legal) can reduce the environmental impact of beer consumption (as opposed to buying pre-bottled beer).