The world's oldest and most popular alcoholic beverage, beer is recorded in the written history of ancient Egypt and Mesopotamia and may have been brewed as early as the 6th millennium BCE. Today, approximately 35 billion gallons of beer are sold each year throughout the world. It is produced by fermenting sugars derived from starch-based materials, including malted(麦芽の)barley and wheat, as well as millet(キビ、アワ)in Africa, potato in Brazil, and agave(リュウゼツラン)in Mexico.