What is "cream of tartar"?

Cream of tartar, also known as potassium bitartrate, is a powdery white substance that is a byproduct of wine production. It is commonly used in baking as a leavening agent and stabilizer. Cream of tartar is acidic and reacts with baking soda to produce carbon dioxide gas, which helps baked goods rise. It is often used in recipes for cakes, cookies, and meringues to achieve a lighter texture and better volume. In addition to its leavening properties, cream of tartar is also used to stabilize egg whites when making meringue, preventing them from collapsing and improving their volume and stability. Beyond baking, cream of tartar is used in some cleaning and household applications, such as removing stains and cleaning metals.