What is a common ingredient used as a leavening agent?

A common ingredient used as a leavening agent is baking powder. Leavening agents are substances that cause dough or batter to rise by producing gas during the baking process, which creates air pockets in the mixture, resulting in a light and fluffy texture in baked goods. Baking powder, specifically, is a chemical leavening agent that contains a combination of an acid and a base, typically baking soda (a base) and cream of tartar (an acid), along with a moisture-absorbing component, usually cornstarch. When moistened and heated, baking powder releases carbon dioxide gas, which helps the structure of the baked item expand and rise.

In contrast, sugar is primarily used for sweetness and may have some effects on the texture but does not act as a leavening agent. Flour serves as the main structural component in baked goods, providing gluten and backbone, but it does not leaven. Butter functions mainly as a fat that adds flavor and moisture but does not contribute to the rising process. Therefore, baking powder is the ingredient specifically designed to create the leavening effect necessary for many baked items.