A door is a movable structure used to open and close an entrance, typically consisting of a panel that swings on hinges or that slides or spins inside a space. The door is used to control the physical atmosphere within a space by enclosing the air drafts, so that interiors may be more effectively heated or cooled. Doors act as a barrier to noise. Most of them are equipped with locking mechanisms to allow entrance to certain people and keep out others. The doors that do not provide access to the outside of the house are called Interior doors, such as doors found on closets, bathrooms, bedrooms and any other enclosed area of the house.

(http://en.wikipedia.org/wiki/Hinged_door#Hinged_doors)

(http://www.homedit.com/types-of-interior-doors-for-home/)