The scientific name for the species of yeast used in baker's or brewer's yeast is Saccharomyces cerevisiae. This species of yeast has been used for baking, winemaking and brewing for hundreds of years.
Baker's yeast is used as a leavening agent in baking. During the baking process, the fermentation of the yeast releases carbon dioxide, causing the bread to rise. The ancient Egyptians are thought to be among the first to discover and use yeast in breadmaking. Historically the yeast used in baking and brewing were identical as many bakers bought the barm, a yeast-filled foam, created in the brewing process to use in baking. Today, the strains for baking and brewing are different.