The full form of AWACS is Airborne Warning and Control System.

AWACS, abbreviation of Airborne Warning And Control System, a mobile, long-range radar surveillance and control centre for air defense. The system, as developed by the U.S. Air Force, is mounted in a specially modified Boeing 707 aircraft. Its main radar antenna is mounted on a turntable housed in a circular rotodome 9 m (30 feet) in diameter, elliptical in cross-section, and 1.8 m deep at its centre. The radar system can detect, track, and identify low-flying aircraft at a distance of 370 km (200 nautical miles) and high-level targets at much greater distances. It also can track maritime traffic, and it operates in any weather over any terrain. An airborne computer can assess enemy action and keep track of the location and availability of any aircraft within range. The communications system, enabling the control of friendly aircraft in pursuit of enemy planes, operates over a single channel, secure from enemy interception, that is also relatively immune to jamming because of its high speed.

The first production-model AWACS entered service in 1977. The U.S. Air Force uses the AWACS, which it designates as E-3, as a command and control centre for units of its Tactical Air Command and also for command and control activity in its North American Air Defense Command (NORAD). NATO also uses the system.

An airborne early warning and control (AEW&C) system is an airborne radar picket system designed to detect aircraft, ships and vehicles at long ranges and perform command and control of the battlespace in an air engagement by directing fighter and attack aircraft strikes. AEW&C units are also used to carry out surveillance, including over ground targets and frequently perform C2BM (command and control, battle management) functions similar to an Air Traffic Controller given military command over other forces. When used at altitude, the radar on the aircraft allows the operators to detect and track targets and distinguish between friendly and hostile aircraft much farther away than a similar ground-based radar. Like a ground-based radar, it can be detected by opposing forces, but because of its mobility and extended sensor range, it is much less vulnerable to counter-attacks.

AEW&C aircraft are used for both defensive and offensive air operations, and are to NATO and US-trained or integrated air forces what the combat information center is to a naval warship, in addition to being a highly mobile and powerful radar platform. The system is used offensively to direct fighters to their target locations, and defensively, directing counterattacks on enemy forces, both air and ground. So useful is the advantage of command and control aircraft operating at a high altitude, that some navies operate such aircraft from their warships at sea. In the case of US Navy, the Northrop Grumman E-2 Hawkeye AEW&C aircraft is assigned to its supercarriers to protect them and augment their onboard command information centers (CICs). The designation airborne early warning (AEW) was used for earlier similar aircraft, such as the Fairey Gannet AEW.3 and Lockheed EC-121 Warning Star, and continues to be used by the RAF for its Sentry AEW1, while AEW&C (airborne early warning and control) emphasizes the command and control capabilities that may not be present on smaller or simpler radar picket aircraft. AWACS (Airborne Warning and Control System) is the name of the specific system installed in the E-3 and Japanese Boeing E-767 AEW&C airframes, but is often used as a general synonym for AEW&C.