A fireplace is a structure made of brick, stone or metal designed to contain a fire. Fireplaces are used for the relaxing ambiance they create and for heating a room. Modern fireplaces vary in heat efficiency, depending on the design. Historically they were used for heating a dwelling, cooking, and heating water for laundry and domestic uses. A fire is contained in a firebox or firepit; a chimney or other flue allows exhaust to escape. A fireplace may have the following: a foundation, a hearth, a firebox, a mantelpiece; a chimney crane (used in kitchen and laundry fireplaces), a grate, a lintel, a lintel bar, overmantel, a damper, a smoke chamber, a throat, and a flue. On the exterior there is often a corbeled brick crown, in which the projecting courses of brick act as a drip course to keep rainwater from running down the exterior walls.