Cream of tartar is a white, powdery substance derived from the sediment left in wine barrels during the fermentation process. Its chemical name is potassium bitartrate, and it is commonly used in cooking and baking. It acts as a stabilizer for egg whites, helping them to maintain their structure when whipped, and it can also prevent sugar from crystallizing in recipes. In addition to its culinary uses, cream of tartar can serve as a leavening agent when combined with baking soda. This combination produces carbon dioxide gas, which helps baked goods rise. It is often found in recipes for meringues, cakes, and cookies.