Beer is a brewed and fermented, alcoholic beverage. Malted grain provides a starchy source of sugar which yeast converts through fermentation into ethyl alcohol (a.k.a. ethanol aka drinking alcohol).
Beer-like beverages were first developed around 15,000 years ago, though these prototypes were not like what we think of beer today. Most used preservative adjuncts instead of bittering-preservatives like hops. Egyptian pictographs show beer being made as long as 9,000 years ago, and a written history of beer production was first recorded in China c. 5000 years ago. In 1634, the first patent related to the production of beer was issued; it related to the most efficient use of fuel to dry malts.
There are four recognized ingredients of beer: barley, water, hops, and yeast. The Reinheitsgebot, passed in 1516, was the German beer purity law. It forbade beers to include any ingredient beyond the first three listed above–yeast wasn’t added until 1857. Eventually wheat was added, and the Reiheitsgebot remained in effect until 1993.
Beer falls into two main categories derivative of the type of yeast used and the fermentation temperatures required by them: ale yeast and lager yeast. Ale was the first type of beer historically. It is fermented at warmer temperatures, usually the upper 60s F, and is ready to drink in a shorter period of time. Lager is fermented at much colder temperatures, the low 50s F, for a longer time. Lagering refers to the process of storing beers at near freezing temperatures, to produce a mellow and smoother brew.
Beers typically have an ABV ranging between 4 – 9%. Some higher gravity beers, such as barleywines, can clock in at 12% ABV or even higher.
The flavor of beers present are determined by the characteristics of the malts, yeast, hops, and water used in their production.
An extraordinary amount of beverages are recognized as beers, though the 2015 Beer Judging Certification Program (BJCP) recognizes 34 distinct styles, with many unique sub-styles contained within each. Beers are generally judged on their overall impression, appearance, aroma, and mouthfeel.