An air base is an airfield that serves mainly for the care of military aircraft, with all the support facilities necessary for military aviation. An air base is adapted for the movement of military aircraft and also has adequate facilities for such aircraft, for the weapons used by them (conventional or atomic bombs, missiles, etc.) and for pilots and officials (dormitories, for example).

The usual thing is air bases with aircraft assigned to that base: an example is the 78th Wing (Armilla). There are also "Parking Bases", which are those that do not have any aircraft and are used for the deployment of aircraft from other bases. In this way, the chances of destroying aircraft on the ground are reduced and their range and coverage area is increased. These bases usually have all the infrastructure prepared for the immediate deployment of the aircraft, so that they act as if they were at their home base. Secondarily, they are used for planes and pilots to rest: an example is the Malaga Air Base"), which, in addition to being a civil airport, usually acts as a secondary base for Torrejón (12th Wing with F-18 aircraft) in case of crisis.

Unlike civilian airports, air bases produce low levels of noise pollution. For security reasons, most are located in not very populated areas, far from large urban centers. The distance between the air base and urban centers is not of much importance for a military base, since the air pollution caused by air bases is less than that of civil airports of similar size, given the much lower vehicle traffic at the airport. Furthermore, at air bases there is very little flying outside office hours, which, unlike a civil airport, also means that their noise footprint is greatly reduced. These are the reasons why the Getafe city council has opposed the conversion of the Getafe Air Base into a civil airport several times.

An example of an air base are aircraft carriers, which have some particularities, such as their mobility, the smaller landing strip and the use of catapults on the runways to help aircraft take flight in takeoff operations.