Have you ever come across a recipe that says "Grease a pan" and then another that says "Grease and flour a pan"? Have you wondered why one recipe just has to be greased whereas another has to be greased and floured?
Greased means to rub the inside of a cake, loaf or muffin pan with grease - normally butter, but more commonly now, non-stick spray, to prevent the baked item from sticking to the inside of the pan.
Greased and Floured means to rub the inside of the pan with a grease normally butter or non-stick spray and then lightly dust the inside of the pan with flour, tapping any excess flour out of the pan. This process is usually used when baking cakes that have a high sugar content or contain fruit. It's used to prevent the cake from sticking to the pan. It's also used when baking with heavily decorated pans such as novelty pans, to prevent sticking.
If you're making a chocolate cake and the recipe instructs to grease and flour a pan, substitute the flour with unsweetened cocoa powder, the cocoa blends in with the color of the cake rather than giving the cake a white halo.