beacons

A beacon is a signaling device designed to attract attention or convey information at a distance. Beacons are used to mark locations, guide travelers or vehicles, and warn of hazards. They have taken many forms, from simple fires on hilltops to modern electronic transmitters, and span various domains including navigation, safety, and communications.

Historically, visual beacons have included bonfires, smoke signals, and towers with lamps. Lighthouses are coastal beacons that emit a rotating light and often sound a fog signal to aid maritime navigation. Aviation uses runway beacons and rotating lights to mark facilities and approach paths. Today, visual beacons often rely on electric lamps or LEDs and may be solar-powered.

Radio beacons transmit signals for navigation, distress, or location. In aviation and marine contexts, NDBs and VORs are radio beacons used to determine position or guide routes. Emergency beacons, such as EPIRBs, PLBs, and ELTs, broadcast distress signals via satellites or radio networks to facilitate rescue.

In information technology, beacons refer to devices or signals that announce the presence of a wireless network or service. Wi-Fi access points send periodic beacon frames to synchronize clients. Bluetooth Low Energy beacons broadcast identifiers that can be used by apps to determine proximity to a physical location.