Beer

Beer is the world's oldest and most popular alcoholic beverage. It is produced by the fermentation of sugars derived from starch-based material — the most common being malted barley; however, wheat, corn, and rice are also widely used, usually in conjunction with barley. Less widely used starch sources include millet, sorghum and cassava root in Africa, potato in Brazil, and agave in Mexico, among others.
The starch source is steeped in water, along with certain enzymes, to produce a sugary wort which is then flavoured with herbs, fruit or most commonly hops. Yeast is then used to cause fermentation, which produces alcohol and other waste products from anaerobic respiration of the sugars. The process of beer production is called brewing.
Beer uses many varying ingredients, production methods and traditions. The type of yeast and production method may be used to classify beer into ale, lager and spontaneously fermented beers. Some beer writers and organizations differentiate and categorize beers by various factors into beer styles. Alcoholic beverages fermented from non-starch sources such as grape juice (wine) or honey (mead), as well as distilled beverages, are not classified as beer.