Global Positioning System (GPS)
"The Global Positioning System (GPS) is one of the global navigation satellite systems (GNSS). Its fundamental technique involves measuring the ranges between the receiver and a few simultaneously observed satellites, and the positions of the satellites are forecasted and broadcasted along with the GPS signal to the user. Through several known positions (of the satellites) and the measured distances between the receiver and the satellites, the position of the receiver can be determined. The position change, which can also be determined, is then the velocity of the receiver. The most important applications of GPS are positioning and navigation." (Xu and Xu 2007)
Xu, Guochang, and Yan Xu. GPS. Springer-Verlag Berlin Heidelberg, 2007.