The traditional English pound cake used equal parts of butter, flour, sugar, and eggs to produce a heavy, rich cake. This was the first butter cake. The invention of baking powder during the 19th century made it possible to have lighter, fluffier cakes using these same ingredients, making the modern butter cake.
Butter cakes are often made by beating the butter and sugar until fluffy. This is called creaming. Eggs are added, then the other ingredients. Butter cakes taste best when stored at room temperature, because they dry out and lose taste when refrigerated.
Butter cakes are high in fat because they contain so much butter.