Movable barrier installed in the entry of a room or building to restrict access or provide visual privacy. Early doors were hides or textiles. With monumental architecture came pivoting doors of rigid, permanent materials; important chambers often had stone or bronze doors. Pompeiian doors looked much like modern wooden doors; they were constructed of stiles (vertical planks) and rails (horizontal planks) fastened together to support panels and occasionally equipped with locks and hinges. The typical Western medieval door was of vertical planks backed with horizontal or diagonal bracing. In the 20th century, a single, hollow-core panel door became most common. Other types include the revolving door, folding door, sliding door (inspired by the Japanese shoji), rolling door, and Dutch door (divided horizontally so that the lower or upper part can be opened separately).