A balise is an electronic beacon placed between the rails of a railway as part of an automatic train protection system.

The French word "balise" is used to distinguish these beacons from other kinds of beacon.

Balises typically need no power source and are energized by a radio frequency aerial mounted on the train.

The balise sends back to the train information about the geometry of the line (such as curves, gradients and speed limits) and the position of any signals.

Balises are typically deployed in pairs so that the train can distinguish direction A-B from direction B-A.