Sponge cake is a cake

Cake

Cake is a form of bread or bread-like food. In its modern forms, it is typically a sweet and enriched baked dessert. In its oldest forms, cakes were normally fried breads or cheesecakes, and normally had a disk shape...

 based on flour

Flour

Flour is a powder which is made by grinding cereal grains, other seeds or roots . It is the main ingredient of bread, which is a staple food for many cultures, making the availability of adequate supplies of flour a major economic and political issue at various times throughout history...

 (usually wheat

Wheat

Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...

 flour), sugar

Sugar

Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...

, and egg

Egg (food)

Eggs are laid by females of many different species, including birds, reptiles, amphibians, and fish, and have probably been eaten by mankind for millennia. Bird and reptile eggs consist of a protective eggshell, albumen , and vitellus , contained within various thin membranes...

s, sometimes leavened with baking powder

Baking powder

Baking powder is a dry chemical leavening agent used to increase the volume and lighten the texture of baked goods such as muffins, cakes, scones and American-style biscuits. Baking powder works by releasing carbon dioxide gas into a batter or dough through an acid-base reaction, causing bubbles in...

 which has a firm, yet well aerated structure, similar to a sea sponge. A sponge cake may be produced by either the batter method, or the foam method

Foam cake

Foam Cakes are cakes with very little fatty material such as butter, oil or shortening, and are leavened primarily by the air that is beaten into the egg whites that they contain. They are in contrast to butter cakes which contain shortening, and baking powder or baking soda for leavening...

. Typicially the batter method in the U.S. is known as a butter or pound cake

Pound cake

Pound cake refers to a type of cake traditionally made with a pound of each of four ingredients: flour, butter, eggs, and sugar. The traditional recipe makes a cake much larger than most families can consume, and so the quantity is often changed to suit the size of the cake that is desired...

 while in the U.K. it is known as Madeira cake

Madeira cake

Madeira cake is a sponge cake in traditional English cookery.The Madeira Cake has a firm yet light texture, eaten with tea or rarely for breakfast and is traditionally flavoured with lemon. Dating back to an original recipe in the 18th century or 19th century, it is not unlike a simple pound cake...

 or Victoria sponge cake. Using the foam method a cake may simply be known as a sponge cake or in the U.K.