The hangar is a place used to store and maintain both aircraft and airships,[1]​ generally large in size and located at airports.

Also called a hangar, on aircraft carriers, is the place where, for a similar purpose, the planes spend the night and are assembled. This can be armored, to protect itself from air attacks, or it can be dispensed with to gain space, as was the case with the Japanese aircraft carriers, these being more vulnerable to air attacks. In any case, it is a highly functional part of aircraft carriers, since it is where aircraft maintenance is done.[2]​.

Hangar structures must have large entrances for aircraft; the larger the aircraft, the greater the opening in the air zone (door opening area). Therefore, they are structures made by specialists, both from the structural point of view and from the installation point of view. For example, hangar doors form a world apart from conventional doors, having to allow their operation while admitting the deformations of the structure; they can open vertically with canvas and horizontally with metal plates.[3]​.

Hangars can be classified by the distance left for aircraft entry, that is, the width of the air zone left without pillars:

The XXL hangars allow the entry of the largest aircraft in the world, in addition to being able to house a greater number of smaller aircraft in their facilities. Regarding size, it is important to highlight that the tail height is related to the wingspan of the aircraft, so large airplanes, in addition to needing pillar-free enclosures, require great headroom. In the case of larger aircraft, this free height can be up to 30m.

Maintenance hangars usually have a set of overhead cranes and/or telescopic platforms capable of covering the entire surface of the hangar. These elements are installed by suspending themselves from the structure, transmitting the load to it.

Hangars, in addition to the structure with large spans and large doors, usually have complex fire protection installations, special floor surface finishes, powerful lighting systems, etc.

Many warships carry aircraft and have hangars for storage and maintenance. Such hangars may be located adjacent to the flight deck on cruisers, destroyers, frigates, and corvettes, or may be hidden beneath the flight deck and have elevators for storing aircraft aboard aircraft carriers, helicopter carriers, and amphibious assault ships.