Automatic Dependent Surveillance–Broadcast (ADS-B) is a surveillance technology in which an aircraft determines its position via satellite navigation or other sensors and periodically broadcasts it, enabling it to be tracked.

Real-time precision, shared situational awareness, advanced applications for pilots and controllers. ADS-B improves safety and efficiency in the air and on runways, reduces costs, and lessens harmful effects on the environment.

A means by which aircraft, aerodrome vehicles and other objects can automatically transmit and/or receive data such as identification, position and additional data, as appropriate, in a broadcast mode via a data link.

ADS-B is automatic because no external stimulus is required; it is dependent because it relies on on-board systems to provide surveillance information to other parties. Finally, the data is broadcast, the originating source has no knowledge of who receives the data and there is no interrogation or two-way contract.