A wide variety of beers, usually ales, that traditionally include a high proportion of wheat and have undergone a process that makes them sour. The acidity of these beers varies, depending on the origin of the beer and the aims of the brewer. Sour beers can be pure and fresh or include various bacteria and yeast varieties, such as Brettanomyces, which lends the beer an aroma and taste that includes hints of hay, countryside and Band-Aid. Some are fermented along with fruit such as cherries. These beers originated in Belgium and Germany, but they are becoming increasingly popular in other countries, particularly the United States. Alcohol content can be from 3% to 8%.