Brewing is a complex process with a history some 10,000 years long. The inhabitants of Britain were brewing beer long before they began speaking English around 15 centuries ago. Given the richness of the English tongue, and the affinity of its speakers for beer, it's hardly surprising that a large body of specialised terms has accumulated around beer and brewing. This growing cross-referenced lexicon aims to help you cut through the argot!

ABV - abbreviation for Alcohol By Volume, the alcoholic strength of a drink expressed as a percentage. Most beers have an ABV in the range of 3-8%.

Alcohol - a group of organic compounds with the general formula CnH2n+1OH. Fermentation produces several types of alcohol: primarily ethanol (that can get you drunk) but also fusel alcohols (that can taste unpleasant and contribute to your hangover).

Ale - historically referring to unhopped fermented beverages, during the 15th century they were supplanted by beers, which contained hops. Nowadays that distinction has disappeared - almost all ales are hopped - and the term tends to refer to a British style of beers, top fermented at warmer temperatures and cask conditioned.

Alpha Acids - The constituent of hop resin that imparts bitterness to a beer. Boiling accentuates the flavour imparted by alpha acids, so hop varieties with high alpha acids are usually added to the copper early in the boil to extract the maximum flavour from the hops. The reverse is true of beta acids.

Amylase - An enzyme present in germinating barley that converts starch into the smaller saccharides: glucose, maltose and other sugars. Starch polymers found in malt are too large to be digested by yeast, but glucose and maltose are easily converted into alcohol and CO2. Adjusting the temperature in the mash tun controls the enzyme activity and determines how much of the starch is converted into each of the sugars. This determines the final strength and sweetness of the beer.

Aroma Hops - Hops high in beta acids used to impart aroma to a beer. Aroma hops are added late in the boil or sometimes after boiling.

Aspirator - alternative name for a cask breather.

Barley - common name for the cereal grass Hordeum vulgare. Most beers are brewed from barley grains. Common varieties include Maris Otter, Optic and Pearl.

Barm - Frothy head formed by yeast during top fermentation.

Barrel - a 36 gallon ale cask.

Beer - an alcoholic beverage brewed from malted grain, especially barley, and generally infused with hops. Ale, which historically was a distinct beverage, is nowadays a type of beer.

Beer engine - alternative name for a hand pump.

Beta Acids - The constituent of a hop resin that imparts aroma to a beer. Boiling destroys the aroma imparted by beta acids, so hop varieties with high beta acids are usually added to the copper late in the boil to ensure the maximum hop aroma is retained. The reverse is true of alpha acids.

Bittering Hops - Hops high in alpha acids used to impart bitterness to a beer. Bittering hops are added early in the boil.

Boil - part of the brewing process: the wort is transferred to a copper and boiled with hops to produce a bitter wort.

Bottle conditioning - putting beer unpasteurised into bottles where it undergoes natural secondary fermentation, as opposed to pasteurising it before bottling. This allows the beer to retain and further develop its flavours right up to the time it is served.

Bottom fermentation - fermentation performed by a yeast that gathers at the bottom of the beer and produces no head. Most lagers are brewed in this way.

Brewing - the process of making beer, primarily from water, barley, yeast and hops. The main stages of the brewing process are malting, mashing, lautering (a stage specific to lager), boiling and fermentation, after which the beer may be cask conditioned, kegged or bottled. A simplified description of the brewing process can be found here.

Bright beer - beer that has had all yeast removed and is therefore clear.

Bright nine - a firkin of bright beer.

Burtonising - adding calcium sulphate to water to mimic the hard water of Burton-on-Trent, which is considered perfect for brewing.

Burton Union - alternative name for the Union System.

Butt - a 108 gallon ale cask, equivalent to three barrels.

CAMRA - the CAMpaign for Real Ale, founded in 1971 to campaign for Real Ale, pubs and drinkers' rights, and Europe's most successful consumer organisation. Publishers of the Good Beer Guide and organisers of the Great British Beer Festival.

Cask - a container into which unpasteurised ale is placed and allowed to continue to condition.

Cask breather - device which admits carbon dioxide at blanket pressure into a cask to replace the beer as it is drawn off. This extends the life of a cask ale once tapped and spiled. CAMRA disapproves of the use of these, and instead advocates stocking a smaller range of ales, or smaller casks such as pins

Cask conditioning - putting beer unpasteurised into casks where it undergoes natural secondary fermentation, as opposed to pasteurising it and putting it into kegs. This allows the beer to retain and further develop its flavours right up to the time it is served. Sometimes the cask will be given additional yeast or even dry hopped. Cask conditioning is one of the defining characteristics of Real Ale.

Copper - vessel in which wort is boiled with hops before fermentation.

Craft Brewer - A brewery where the brewing process is controlled by hand rather than by computer.

Demand valve - alternative name for a cask breather.

Dry hopping - adding whole hops to cooled wort in the fermenting vessel or to beer in the cask.

Enzymes - proteins that activate and accelerate chemical reactions. Amylase enzymes are particularly good at breaking down starches into sugars, a process encouraged in cereal grains during the malting process.

Ethanol - a type of alcohol with the chemical formula C2H5OH. Also known as grain alcohol, it is the main product of fermentation.

Fermentation - part of the brewing process: in a fermenting vessel, yeast is introduced to the wort where it transforms the sugars into alcohol and carbon dioxide.

Fermenting vessel - the container in which fermentation converts the wort into beer.

Finings - a thick liquid added to beer after fermentation to help it clear. Isinglass, a substance obtained from the swimbladders of fish, is commonly used.

Firkin - a 9 gallon ale cask - the most common size for real ale festivals - equivalent to a quarter of a barrel.

Flocculation - The process in which spent yeast particles clump together to form larger flakes before sinking to the bottom of beer after fermentation. This process is accelerated by use of finings.

Fusel alcohols - any alcohol with a higher molecular weight than ethanol. The name comes from the German for "bad liquor", as at high levels they will give beer an unpleasant "chemical" taste. They often result from high fermentation temperatures.

GBBF - abbreviation for the Great British Beer Festival.

Good Beer Guide or GBG - annual guide to the best pubs across Britain for Real Ale drinkers, published by CAMRA.

Grain alcohol - the common name for ethanol.

Gravity dispense - a method for serving Real Ale: a cask of ale is placed on its side in stillage, and a tap and spile inserted. Although unusual at pubs, it is a common serving method at beer festivals. No gas pressure is required, which is one of the defining characteristics of Real Ale.

Great British Beer Festival - Britain's biggest Real Ale event, held annually in Earl's Court, London and orgnised by CAMRA. Abbreviated to GBBF.

Grist - malt that has been lightly ground to allow the sugars to be released into the wort more easily.

Gyle - essentially a beer batch number. Each time a fermenting vessel is filled a unique number is assigned to the contents by the brewery, starting generally with Gyle 1 at the beginning of each year. Solihull CAMRA's silver jubilee ale was Tunnel Brewery's Gyle 137.

Hand pump - a mechanism used to serve cask conditioned ales, it consists of a lever mounted on the bar top that, when pulled, draws the beer from the cask, which is connected by a pipe. No motor is used and no gas pressure is required, which are defining characteristics of Real Ale.

Hogshead - a 54 gallon ale cask, equivalent to one and a half barrels.

Hopback - airtight hop container between the copper and the fermenting vessel. Wort is filtered through the hops before being rapidly cooled for fermentation. More hop aroma is retained than from hops added during boiling.

Hops - small green flowers of the climbing vine Humulus lupulus, they give beer its bitterness and much of its aroma. Common varieties include Cascade, Challenger, Fuggles, Goldings and Saaz.

Infusion mashing - method of mashing used in brewing ales, performed at a uniform temperature in a mash tun which takes the place of a lauter tun.

Isinglass - extract of fish swimbladders used as finings.

Keg - a container for pasteurised beer intended to be served under gas pressure, generally made of steel.

Keystone- the soft plastic bung in the circular face of a cask (by the lowest point when the cask is laid down) into which the tap is hammered.

Kilderkin or Kil - an 18 gallon ale cask, equivalent to two firkins or a half barrel.

Kilning - The process of heating and drying barley in a kiln to stop its germination once the grain's starches have been converted to sugars but before they are used up in growing the shoot (acrospire). Kilning at lower or higher temperatures produces the different types of malt: Lager Malt, Pale Malt, Crystal Malt, Amber Malt, Brown Malt, Chocolate Malt and Black Malt.

Lager - beer which has been bottom fermented at cool temperatures and then lagered. It is generally then pasteurised before putting into kegs or bottles, and should be served cold.

Lagering - storing beer at low temperatures to remove sharp flavours. Lagering can take weeks or even months.

Late Hopping - Adding aroma hops to the copper near the end of boiling. This creates hop aroma in a beer without increasing bitterness.

Lautering - part of the brewing process: the separation of the mash into wort and spent grain. The term is used primarily in the brewing of lagers, where it involves mashout, recirculation and sparging. For ales, which use infusion mashing, the wort is simply drained through slotted plates in the bottom of the mash tun and into the copper before sparging.

Liquor - simply the water used for brewing.

Malt - barley that has been through the malting process.

Malting - part of the brewing process: a cereal - most commonly barley - is made to germinate and then kilned before a plant grows. This converts the cereal's natural starches into fermentable sugars.

Mash - the mixture of water and crushed, malted barley undergoing mashing.

Mashing - part of the brewing process: mixing water into crushed, malted barley and allowing it to absorb the fermentable sugars to produce wort.

Mashout - part of the lautering stage in the brewing process: the temperature of the mash is raised to stop the enzymes converting starches into fermentable sugars.

Mash tun - vessel in which crushed malted barley is mashed with water.

Microfiltering - a method of removing yeast from a beer to extend its shelf life, typically used before bottling in preference to pasteurisation.

Original Gravity or OG - a measure of how much sugar is in the wort before fermentation. This gives an indication of how strong the beer will be after fermentation when the yeast has converted the sugar into alcohol.

Paraflow - a heat exchanger, used to simultaneously cool the wort after the boil and heat liquor for the next mash.

Pasteurisation - high-temperature treatment of beer to kill all traces of yeast in a beer to extend its shelf life, typically used before bottling. CAMRA disapproves of pasteurisation as it removes flavour and character and adds a distinctive "burnt sugar" flavour.

Parti-gyle- a system, very common in centuries past, of drawing off the wort from the mash tun in stages to produce beers of diminishing strength, strong ale or barley wine, then a more ordinary beer, and finally a weak small beer. These three brews were sometimes called XXX, XX and X respectively.

Pin - a 4.5 gallon ale cask, equivalent to a half firkin or an eighth of a barrel.

Pint - British Imperial measure of dry or liquid volume, equivalent to 0.568 litres or 20 fluid ounces. The US liquid pint is significantly smaller at 0.473 litres or 16 US fluid ounces (fractionally larger than Imperial fluid ounces). Thought to originate from the Latin "picta" meaning "painted" - a mark painted on a container indicating the correct volume

Pump clip - plate attached to the front of a hand pump with much the same appearance and function as the label on a beer bottle.

Puncheon - a 72 gallon ale cask, equivalent to two barrels.

Racking - Draining the ale from the fermenting vessel into casks after fermentation is complete, leaving most of the unwanted trub behind.

RAIB - abbreviation for Real Ale in a Bottle.

Real Ale - traditionally brewed ale, unpasteurised and cask conditioned. It should be served without gas pressure by either handpump or gravity dispense, and so is a lot less fizzy than keg beers (but not flat), and should be served cool rather than cold like a lager (but not warm).

Real Ale in a Bottle - traditionally brewed ale, unpasteurised and bottle conditioned. Abbreviated to RAIB.

Recirculation - part of the lautering stage in the brewing process: wort is drawn off from the bottom of the mash and returned to the top, where it will pass again through the grain in order to extract more sugar and filter out mash debris.

Reinheitsgebot - German beer purity law - literally "purity requirement" - dating from 1516 and essentially stating that beer may only contain barley, hops, yeast and water. In 1993 it was replaced by a law allowing additives such and cane sugar and malted wheat but prohibiting unmalted barley.

Shrive - the soft plastic bung in the curved side of a cask (at the highest point when the cask is laid down) into which a spile is inserted.

Small beer - historically, a weak beer made by fermenting the "second runnings" from sparging the spent grain after the main mash. It was a common drink up until the 18th century, as beer was often the only source of drinkable water, and was considered suitable for drinking with breakfast and for giving to children.

Sparging - part of the brewing process: spent grain is drenched with fresh water, which is then drained into the copper, to rinse the remaining sugars into the wort. Historically, this weaker wort, called "second runnings", would have been kept separate and used to make small beer. In lager brewing, sparging is part of the more complex lautering stage in the brewing process.

SPBW - the Society for the Preservation of Beers from the Wood. A precursor to CAMRA, established in 1963 with very similar aims. It still exists, with some 15 branches mainly in the south of England.

Spile - a wooden peg inserted into the shrive in a cask to regulate air flow into the cask, or the act of inserting same into the cask. A soft spile is porous and allows air to flow in freely when the beer is being served. A hard spile stops air flow when the beer is standing.

Starches - a long chain organic molecules with the general formula Cn(H2O)n-1. It is found in large quantities in brewing grains such as barley. The malting process allows enzymes to break starch molecules down into sugars, especially maltose (C12H22O11).

Stillage - A rack or cradle in which ale casks are laid on their side for dispense. The casks are left to lie in the stillage both before and after being tapped and spiled to allow the trub to settle to the bottom. At a beer festival a stillage might consist of scaffolding with wooden wedges to gently tilt the cask forward as it empties. In pubs, sophisticated mechanisms may be used to automatically tilt the cask towards the tap as it becomed lighter. Kegs do not need a stillage, as they are stood upright and emptied under gas pressure.

Sugars - a group of sweet-tasting organic chemicals. The simplest - monosaccharides such as glucose, fructose and galactose - can join into chains to form more complex sugars. For instance a glucose and a fructose molecule form the disaccharide called sucrose (table sugar), and two glucose molecules can join to form another disaccharide called maltose, which is the main source of sweetness in beer. Extremely long chains of saccharides are called polysaccharides (which no longer taste or behave like sugars) the most important of which are starches.

Tap - a valve used for serving beers by gravity dispense. It is inserted into the keystone of a cask, and when opened the beer flows out under its own weight.

Terpene - a type of hydrocarbon, the principal component of the essential oils of many types of plant, such as hops.

Top fermentation - fermentation performed by a yeast that gathers at the top of the beer and produces the distinctive yellow foamy head. Most traditional British beers are brewed in this way.

Torrefied - dried, as opposed to malted. A small amount of torrefied wheat is is generally added to the mash to improve the size and retention of the beer's head.

Tower brewery - a traditional brewery layout using gravity to move ingredients from one brewing process to the next. The liquor tank and grain hopper are at the top, mash tun underneath, copper below that and fermenting vessels at the bottom.

Trub - sediment formed at the bottom of a fermenting vessel, composed mainly of proteins, heavy fats and spent yeast.

Tun - a 216 gallon ale cask, equivalent to six barrels.

Ullage - the amount of empty space in a filled cask.

Underback - a tank via which run-off is transferred from the mash tun to the copper. It is commonly fitted with float switches, which start and stop the pump leading on to the copper depending on the level of liquid in the underback.

Union System or Union sets - an interlinked arrangement of fermentation vessels where the yeast resides in a large trough mounted above the vessels containing the beer.

Valentine Arm - an inverted U-shaped tube used to syphon the run-off from the mash tun into an underback and on into the copper. A revolving joint allows the arm to be tilted to regulate flow.

Venting peg - a tool used to punch through a shrive, and fitted with a short hose to divert any spray into a bucket.

Whirlpool - a vessel used in some breweries to clarify the wort after the boil. The liquid is gently circulated causing solids - mainly hop fragments - to settle in the middle of the vessel and allowing the clear wort to be drawn off from the side.

Wort - liquid obtained by mashing malted barley with water to extract the fermentable sugars, which is then brewed into beer.

Yeast - single-celled living fungi which convert sugars into alcohol, carbon-dioxide and other trace chemicals - a process called fermentation.

Yorkshire Square - traditional square-shaped, 2-storey fermenting vessel once commonly used in Yorkshire. As with the Union System, the barm forms in a separate container above the level of the fermenting vessel.

Zymology or Zymurgy - the science of fermentation. A word principally used to finish brewing lexicons with a flourish.

Zythum - Ancient Egyptian unfermented malt beer or barley wine. A word used, in this context, to upstage brewing lexicons which stop at Zymurgy!

Kevin Clarke, Gordon Clarke