what is cream of tartar used for

Cream of tartar is a dry, powdery, acidic byproduct of winemaking called potassium bitartrate. It is a common leavening agent in baking and is found in baking powder, which is a combination of sodium bicarbonate (baking soda) and acid. Cream of tartar is also used to stabilize egg whites, resulting in a smooth, billowy meringue. It can also prevent sugar from crystallizing, making it useful for simple syrup and chewy cookies. Additionally, cream of tartar can be used as a cleaning agent for metal and porcelain when mixed with water, lemon juice, or vinegar.