Soda bread is a variety of quick bread traditionally made in a variety of cuisines in which sodium bicarbonate (otherwise known as "baking soda", or in Ireland, "bread soda") is used as a leavening agent instead of the traditional yeast. The ingredients of traditional soda bread are flour, baking soda, salt, and buttermilk. The buttermilk in the dough contains lactic acid, which reacts with the baking soda to form tiny bubbles of carbon dioxide. Other ingredients can be added, such as butter, egg, raisins, or nuts. An advantage of quick breads is their ability to be prepared quickly and reliably, without requiring the time-consuming skilled labor and temperature control needed for traditional yeast breads.