Ovens are closed, heated containers which are used for heating, baking, and drying. It is used the most often in cooking and pottery. They provide even, dry heat to all surfaces of food inside them. An indoor oven can have an electric heating element, or be fired by natural gas or coal. Outdoor ovens are often made of brick or clay and are buried in hot coals. An oven which is used for making pottery is called a kiln. An oven used for heating or industrial processes is called a furnace. They are hot inside, and often things come out of them hot.