It is used when the food should not taste of yeast,[1] or when the mixture is not elastic enough to hold bubbles for very long.[2] But sometimes, it has a metallic taste.[3] Because carbon dioxide is made faster by baking powder than yeast, breads made with it are called quick breads.
Most baking powders are made up of an alkaline (usually baking soda), one or two acid salts, and a starch (cornstarch or sometimes potato starch). Baking soda is where the carbon dioxide comes from,[4] and the acid releases it, like this:[5]