A door is a hinged or otherwise movable barrier that allows ingress into and egress from an enclosure. The created opening in the wall is a doorway or portal. A door's essential and primary purpose is to provide security by controlling access to the doorway (portal). Conventionally, it is a panel that fits into the portal of a building, room, or vehicle. Doors are generally made of a material suited to the door's task. Doors are commonly attached by hinges, but can move by other means, such as slides or counterbalancing.
Drawings by Frank Gaylard from: Fisher, Roger C. 1992. Visual Lexicon of the South African Dwelling. Cape Town: Unibook. p, 18-19, 22.