Baking powder is a chemical leavening agent. It is a mixture of a carbonate and a weak acid, and is used for increasing the volume and lightening the texture of baked goods. Baking powder is most often used to leaven muffins, pancakes, or other mixtures that use a loose batter. Batters are not strong enough to hold in gases for long periods of time so they need quick acting leavening action like that created with baking powder.