Door

A door is a structural element found in many houses and other building?s. A door's purpose is to regulate material transfer to rooms behind the door. A door is usually fastened in a doorway, that is a frame constructed around the edges of a hole in a wall? or other containing structure.

Doors are commonly used for reducing air drafts and creating an enclosed space that can be heated or cooled more effectively. The use of doors is essential in colder climes where heating would be very difficult without them, and similarly in climates where air conditioning is used.

Another very common use of doors is regulation of access to the rooms behind the door. Combined with various types of lock?s, doors become important safety measures.

Many kinds of doors have specific names, depending on their intended purpose. The most common variety of door consists of a single rigid panel that fills the doorway, hinge?d 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 independant panels hinged on each side of the doorway. A "trap" door is a door that is oriented horizontally in a floor? or ceiling?, often accessed via a ladder?.