Pie dough refers to a mixture of flour, water and fat (usually butter or shortening) that is used to create the crust for pies. The dough can be made with different variations in ingredients, such as adding sugar, salt, eggs or milk, depending on the desired texture and flavor of the final product. Once rolled out and placed into a pie pan, it forms a barrier between the filling and the plate, keeping everything contained while also providing a delicious taste.