A chair is a piece of furniture with a raised surface supported by legs, commonly used to seat a single person. Chairs are supported most often by four legs and have a back. Chairs can be made from wood, metal, or other strong materials. In some cases, multiple materials are used to construct a chair; for example, the legs and frame may be made from metal and the seat and back may be made from plastic. Chairs may have hard surfaces of wood, metal, plastic, or other materials, or some or all of these hard surfaces may be covered with upholstery or padding.