A door is a usually hinged or sliding panel that covers a generally
floor-length opening in a wall (or other partition), and can be moved to
leave the opening accessible, or to close it more or less securely.
Doors are nearly universal in structures of all kinds (especially houses
and other buildings), allowing passage between inside and outside, or
among internal rooms. Doors are also found in vehicles, cupboards,
The purpose of a door opening is:
* to allow people, animals and objects to pass
* for ventilation
The purpose of a door closure is:
* preventing passage of infiltration air; reducing air drafts and
creating an enclosed space that can be heated or cooled more effectively
(revolving doors are especially efficient for this purpose)
* privacy, and noise reduction
* keeping occupants inside a vehicle
* regulation of access, especially when combined with various types of
* for aesthetics (e.g. cupboard doors cutting off view of the contents)
* to help prevent the spread of fire
Doors and doorways can also appear in metaphorical or mystical
situations; for example, a spiritualist might speak of "opening a door
to the other world". Doors can have ritual purposes (one example
concerns the doorkeeping duties of the Gentleman Usher of the Black
The term door can refer either to the opening or to the movable panel or
panels which closes it. The term doorway can be used to refer
specifically to the opening. When framed in wood for snug fitting of a
door, the doorway consists of two vertical jambs on either side, a
lintel or head jamb at the top, and perhaps a threshold at the bottom.
When a door has more than one movable panel, one of the panels may be
called a leaf.
See door furniture for a discussion of attachments to doors such as door
handles and doorknobs
Types of Door
A door may slide along tracks, pivot on
The door may also slide between two wall panels (pocket door).
In the case of rotation, the axis of rotation is usually vertical, but
e.g. for garage doors often horizontal, above the door opening.
Sometimes the axis of rotation is, with a special construction, not in
the plane of the door, on the other side than that in which the door
opens, to reduce the space required on the side to which the door opens.
This is sometimes the case in a train, for the door to the toilet,
Many kinds of doors have specific names, depending on their purpose. The
most common variety of door consists of a single rigid panel that fills
the doorway, hinged along one side so that it can fold away from the
doorway in one direction but not in the other. Many variations on this
basic design are possible, such as "double" doors that have two adjacent
independent panels hinged on each side of the doorway.
A trapdoor is a door that is oriented horizontally in a floor or
ceiling, often accessed via a ladder.
A stable door is divided in half horizontally. The top half can be
opened to allow the horse to be fed, while the bottom half can be closed
to keep the animal inside. Stable doors are also known as dutch doors.
A swing door has special hinges that allow it to open either outwards or
inwards, and is usually sprung to keep it closed. Saloon doors are a
pair of lightweight swing doors often found in public bars. Saloon
doors, also known as cafe doors, often use double action hinges, which
will return the door to the center, regardless of which direction it is
opened, due to the double action springs in the doors.
A blind door is a door with no visible trim or operable components. It
is designed to blend with the adjacent wall in all finishes, and
visually to be a part of the wall, a disguised door.
An up-and-over door is often used in garages. Instead of hinges it has a
mechanism, often counterbalanced or sprung, that allows it to be lifted
so that it rests horizontally above the opening. Also known as an
A barn door is a door on a barn. It is often/always found on barns, and
because of a barn's immense size (often) doors are subsequently big for
A French door, also called a French window, is a door that has multiple
windows ("lights") set into it, the full length of the door. Traditional
French doors are assembled from individual small pieces of glass and
mullions. These doors are also known as true divided lite[sic] French
doors. French doors made of double-pane glass (on exterior doors for
insulation reasons) may have a decorative grille embedded between the
panes, or may also be true divided lite French doors. The decorative
grille may also be superimposed on top of single pane of glass in the
A louver door has fixed or movable wooden fins (often called slats or
louvers) which permit open ventilation whilst preserving privacy and
preventing the passage of light to the interior. Being relatively weak
structures, they are most commonly used for wardrobes and drying rooms,
where security is of less importance than good ventilation, although a
very similar structure is commonly used to form window shutters.
A flush door is a completely smooth, panelled door, having plywood or
MDF fixed over a light timber frame, the hollow parts of which are often
filled with a cardboard core material. Flush doors are most commonly
employed in the interior of a dwelling, although slightly more
substantial versions are occasionally used as exterior doors, especially
within hotels and other buildings containing many independent dwellings.
A ledge and brace door is a door made from multiple vertical planks
fixed together by two horizontal planks (the ledges) and kept square by
a diagonal plank (the brace).
Mechanism of the sliding door of a lift
Mechanism of the sliding door of a lift
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. In such a configuration, it has the advantage of a very
large opening for moving large objects in and out.
A pet door 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 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.
A bifold door is door unit that has 2 to 4 sections, folding in pairs.
The doors can open from either side for one pair, or fold off both sides
for two pairs. Wood is the most common material, and doors may also be
metal or glass. Bifolds are most commonly made for closets, but may also
be used as units between rooms.
A bypass door is a door unit that has 2 or more sections. The doors can
slide from each direction on an overhead track, sliding past each other.
They are most commonly used in closets, in order to access one side of
the closet at a time. The doors in a bypass unit will overlap slightly,
in order not to have a gap between them.
A pocket door is a door that slides on rails, rather than swinging on
hinges, and, when opened, slides into an open cavity within a wall.
A sliding glass door is a door made of glass that slides open and
sometimes has a screen. Sliding glass doors are common in many houses,
particularly as an entrance to the backyard. Such doors are also popular
for use for the entrances to commercial structures.
An ambulance door is a back door for a truck or van which consists of
two full-height double doors which open outward from the center. Other
types of door options for these vehicles are roll up doors, hatchback
doors and tailgates.
A false door is a wall decoration that looks like a door. In ancient
Egyptian architecture, this was a common element in a tomb, the false
door representing a gate to the afterlife. They can also be found in the
funerary architecture of the desert tribes (e.g., Libyan Ghirza). It may
have influenced the mihrab in a mosque.
A revolving door is a type of door that typically consists of a
structure with three or four panels that meet in the center and rotate
one way about a vertical axis (sometimes the movement is not in a
circle, but following a more complicated path, a combination of rotation
and translation). Between the point of access and the point of exit the
user walks between two moving panels. The door may be motorized or the
user needs to push the front panel, and the space between two panels may
be designed for multiple users or a single one. This door design is used
primarily to maintain an air seal from the outside, thus minimizing
leaking of climate controlled air from the building and the resulting
expense of compensating for the loss. This type of door is also often
seen as a mark of prestige and glamour for a building and it not unusual
for neighbouring buildings to install their own revolving doors when a
rival building gets one.