Sourdough bread is bread which is fermented with a natural leaven as opposed to a yeast bread which is fermented with fresh or dried baker’s yeast. The health benefits of sourdough are well known, and don’t need to be further expanded, but the definitive taste of sourdough bread is a result of a much longer fermentation process. It is not a vinegary tasting liquid thrown into a yeasted bread to deceive the consumer into thinking they are eating a slowly fermented naturally leavened bread.