Pound cake refers to a type of cake traditionally made with a pound of each of four ingredients: flour, butter, eggs, and sugar. However, the quantity is often changed to suit the size of the cake that is desired. As long as the ratio is preserved, the resulting cake will generally be very similar to that using the traditional quantities. Hence, any cake made with a 1:1:1:1 ratio of flour, butter, eggs, and sugar is also called a pound cake, even if the quantity used is smaller or larger than a pound.
There are numerous variations on the traditional pound cake, with certain countries and regions having distinctive styles. These can include the addition of flavoring agents (such as vanilla extract or almond extract) or dried fruit (such as currants or raisins), as well as alterations to the original recipe in order to change the characteristics of the resulting pound cake. For instance, baking soda or baking powder may be incorporated in order to induce leavening during baking, resulting in a less dense pound cake. A cooking oil (typically a vegetable oil) is sometimes substituted for some or all of the butter, which is intended to produce a more moist cake. "Sour cream pound cake" is a popular variation in the United States, which involves the substitution of sour cream for some of the butter, which also is intended to produce a more moist cake with a pleasantly tangy flavor. Some of these variations may drastically change the texture and flavor of the pound cake, but the name pound cake is often still used.