are aids to navigation
devices. Intentionally conspicuous, beacons help guide navigators to their destinations. Beacon types include radar reflectors, radio beacons
, and sonic or visual signals. Visual beacons range from small, single-pile structures to large lighthouses or light stations and are located on land or in water. Lighted beacons are called lights; unlighted beacons are called daybeacons.
Classically, beacons are fires lit on hills or high places, used either as lighthouses for navigation at sea, or for signalling over land that enemy troops are approaching, and alerting the defense. In the latter iteration, beacons are an ancient form of optical telegraphy, and were always parts of a relay league.
Systems of this kind have existed for centuries over much of the world. Indeed, in Scandinavia many hill forts were parts of beacon networks to warn against invading pillagers.
In Israel beacons were used to show the beginning of the month.
In Wales, the Brecon Beacons were named for beacons used to warn of approaching English raiders.
In England, the most famous examples are the beacons used in Elizabethan England to warn of the approaching Spanish Armada. Many hills in England are named Beacon Hill after these beacons.
Beacons have often been abused by pirates. A fire at a wrong position was used to direct a ship against cliffs or beaches, so the cargo could be looted after the ship sank or ran aground.
In The Lord of the Rings, a series of seven beacons is used as a signaling device between Gondor and Rohan. In the film adaptation of The Return of the King, Gandalf has Pippin light the beacon closest to Minas Tirith. The series is then lit, thereby notifying Rohan's King Théoden that Gondor calls for help in the battle against Sauron.