Some breweries claim their water is substantially better, hence better beer. Mountain spring water is one of the most advertised these days. Hops are plants of the genus humulus used for flavoring beer, giving it a bitter flavor and aroma. Its use today is held as a standard, but in beer's history, hops were only introduced in the late Medieval period. Hop Humulus Lupus Barley and other grains similar to it are high in starch content.
American breweries have a large mix of grains to choose from.
Some Asian brews are made from rice. Russian beer is from kvass, or rye bread. Africans can use teff, millet or grass seeds. The slowly stir the barley. As the wet grain comes in contact with the air, germination begins.