A beacon is an instrument meant to attract attention to a specific location or event. Beacons in combination with certain other instruments or indicators provide vital information that requires urgent attention. All are familiar with the beacons functioning on top of the vehicles of VIPs, ambulances and fire engines.
A lighthouse has a tower and a beacon and airport has them too. Beacons are devices put on the top of a tower and are designed to attract attention to a specific location. This is done in many ways. For example, in the case of a light house a beacon attracts attention by projecting light beam skyward. Beacons can thus function as an ordinary light source which becomes some kind of a landmark for sailors sailing in the dark. They basically help in guiding sailors or pilots to their destination.
In satellite communications, a beacon becomes a tracking device used by control engineers on the ground to monitor the satellite. The beacons used for navigation purpose could either be lighted beacons or unlighted beacons. Radar signals, sound signals or light signals are normally used as medium of navigation. Apart from navigation, beacons could be used for defensive communications as a warning signal on an elevated position.