Glass doors are a movable structure which is used to open and close an entrance, typically consisting of a panel that swings on hinges, slides, or spins inside a space. When open, doors admit people, ventilation, and light. Doors are used to control the physical atmosphere within a space by enclosing air drafts, so that interiors may be more effectively heated or cooled. They are used to secure passages into a building from the exterior for reasons of safety and climate control. Doors are also significant in preventing the spread of fire. Many doors are equipped with locking mechanisms to allow the entrance of certain people while keeping others out.
Doors are used to screen areas of a building for aesthetics, keeping formal and utility areas separate. Architectural doors have numerous general and specialized uses. Doors are generally used to separate interior spaces (rooms, closets, etc.) for privacy, convenience, security, and safety reasons.