What Is Baking Powder?

How baking powder works and why it's essential for light, fluffy baked goods.

Baking powder is a leavening agent that helps baked goods rise by producing carbon dioxide gas when mixed with liquid and heat.
Unlike baking soda, which needs an acid to work, baking powder already contains both an acid (usually cream of tartar) and a base (baking soda), so it works on its own in recipes without extra acidic ingredients.
Most baking powders are "double-acting," meaning they create bubbles twice — once when wet and again in the oven's heat — for a light, fluffy texture.
Kitchen Tip: If your baking powder is older than 6 months, test it by mixing 1 teaspoon into ½ cup of hot water. If it fizzes, it's still good.