Sourdough Bread celebrates this delicious ancient bread that dates back in history to at least 3700 B.C. Sourdough is made by a long fermentation of the dough by using a naturally occurring lactobacilli bacteria and wild yeasts. This type of leavening was used prior to science learning the process of cultivating yeasts. The sour taste and aroma of the Sourdough Bread is still a taste so many people around the world love. So enjoy some Sourdough Bread on Sourdough Bread Day!