Sourdough is a wild fermented culture of flour and water. Over time, yeast from the air mixes with the flour and feeds on its starches and sugars, multiplying slowly to help this mixture of flour and water work its magic. Eventually, gut-healthy bacteria grow, emitting CO2 gas. This process is called fermentation, and it's what creates those gorgeous holes in our sourdough bread. This wonderfully alive mixture is called “sourdough” or “sourdough starter.” It is a natural form of yeast that causes the dough to rise over a long period of time. Chances are, you’re familiar with commercial yeast: “active dry yeast” or “instant yeast”—AKA those little packets in the baking aisle of the grocery store. Commercial yeast is developed in a lab to be super-efficient, meaning it makes dough rise VERY quickly (think: make a loaf of bread in 2 hours quick). So, what makes sourdough, sourdough? The presence of a natural yeast! Really, we should be calling sourdough bread “wild yeast bread.” Sourdough bread relies on natural elements—the yeast chilling in the air, on the flour, on our hands. And a whole lot of time. There are no shortcuts in making sourdough bread, and quite frankly, we wouldn’t make our bread any other way.