Aids to navigation include lighthouses, beacons, buoys, towers, floating aids and permanent structures.
These are all man-made devices that can be used to warn of a danger, to mark a location, or to indicate a safe route. Aids to navigation are placed along coastlines, navigable and non-navigable waters in order to assist the Navigator to determine his or her position in relation to land and hidden hazards.
By day we can identify an aid to Navigation by location, shape, color scheme, auxiliary features (sound signals, racon), and markings, such as name and number.
By night we can identify an aid to Navigation by it’s light.
Each light has three distinctive characteristics: the color, the period and the phase characteristic.