Door is a hinged or otherwise movable barrier that allows ingress and egress into an “enclosure”. The opening in the wall can be referred to as a “portal”. A door’s essential and primary purpose is to provide security by controlling the portal (doorway). Conventionally, it is a panel that fits into the portal of a building, room, or vehicle. Doors are commonly made of a material suited to the task of which it is to perform. Doors are commonly attached by hinges within the portal but can be moved by other means such as slides or counterbalancing.
The door may be moved in various ways (at angles away from the portal, by sliding on a plane parallel to the frame, by folding in angles on a parallel plane, or by spinning along an axis at the center of the frame) to allow or prevent ingress or egress. In most cases, a door’s interior matches its exterior side. But in other cases (e.g., a vehicle door) the two sides are radically different.
