Potassium hydrogen tartrate, also known as cream of tartar, is a white, crystalline powder derived from the sediment left in wine barrels during the fermentation process. It is a byproduct of winemaking and is commonly used in cooking and baking to stabilize egg whites, prevent sugar crystallization, and act as a leavening agent when combined with baking soda. In addition to its culinary uses, potassium hydrogen tartrate has applications in the pharmaceutical industry and can be found in some laboratory settings. It is recognized for its mild acidity and is often used in various chemical reactions and formulations.