Trilateration is the method of determining the position of a point, given the distance to three control points, as opposed to the more commonly known method, triangulation (which is based on the angles between said control points).

Trilateration can be applied to many different areas, e.g. geograpic mapping, navigation (e.g. GPS systems), and due to the progress in electronic distance-measuring it is preferred to triangulation.

(Trilateration has been successfully applied to a positioning system where a number of beacons emit signals, from which a device can determine its position. In this case, however, the device only knows the differences in distance, and a fourth beacon had to be used.)