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. Doors are also used to secure passages into a building from the exterior for reasons of safety and climate control.
Doors also are applied in more specialized cases:
A trapdoor is a door that is oriented horizontally in a floor or ceiling, often accessed via a ladder.
Blast-proof doors are constructed to allow access to a structure but also to provide protection from the force of explosions.
A garden door is any door that opens to a garden or backyard. It is often used specifically for double French doors in place of a sliding glass door (also known as Patio doors). In such a configuration, it has the advantage of a very large opening for moving large objects in and out.
A pet door (also known as a dog door or cat flap) is an opening in a door to allow pets to enter and exit without the main door being opened. It may be simply covered by a rubber flap or it may be an actual kitchen cabinet door hinged on the top that the pet can push through. Pet doors may be mounted in a sliding glass door as a new (permanent or temporary) panel. Pet doors may be unidirectional, only allowing pets to exit. Pet doors may be electronic, only allowing pets with a special electronic tag to enter.
