A pie crust is a baked pastry shell that serves as the base for various types of pies, such as fruit, custard, or savory fillings. Typically made from flour, fat (like butter or shortening), and water, the dough is rolled out and placed in a pie dish. The crust can be either flaky or crumbly, depending on the ingredients and preparation method used. There are two main types of pie crusts: single crust, which covers only the bottom of the pie, and double crust, which has both a bottom and a top layer. Some recipes also include a graham cracker crust, made from crushed graham crackers, sugar, and butter, often used for no-bake pies.