Navigation

(computer science) In a database management system, the techniques provided for locating information within the system.
(engineering) The process of directing the movement of a craft so that it will reach its intended destination; subprocesses are position fixing, dead reckoning, pilotage, and homing.

The process of directing the movement of a craft from one place to another. Navigation involves position, direction, distance, time, and speed.

The process of keeping track of a craft's location by measuring and applying progress from a previous position is called dead reckoning. The location of a craft relative to external reference points such as landmarks or aids to navigation is called piloting. Radio navigation involves determining distances or directions to radio transmitters. Celestial navigation involves the use of celestial bodies. See also Celestial navigation; Dead reckoning; Piloting.

The craft to be navigated may be a ship, small marine craft, land vehicle, aircraft, missile, spacecraft, or any moving object requiring direction or capable of being directed, even an animal or bird. The characteristics of the craft have a significant influence upon the type of navigation and the equipment used. Size, mission, weight and space limitations, and economic factors are important considerations.

Anything used in navigation, whether aboard the craft or external to it, is properly termed a navigational aid. Thus, in addition to onboard navigational equipment, the term includes such external aids as natural landmarks, prominent buildings, or other structures. Although sometimes used synonymously with “navigational aid,” the expression “aid to navigation” is generally restricted to an object or device, external to the craft, established expressly to assist navigation. In this restricted sense, aids to navigation for mariners consist of buoys, beacons, lighthouses, lightships, and navigation sound and electronic transmitters. Aids to navigation for aviators consist primarily of radio ranges and beacons and radio position-fixing transmitters. See also Buoy; Electronic navigation systems; Hyperbolic navigation system; Lighthouse; Marine navigation.