Refers to the technology originally developed by the U.S. Department of Defense and consisting of 24 satellites that continuously transmit signals globally. In conjunction with receivers on Earth, the system uses triangulation to quickly and accurately determine the latitude, longitude, and altitude of a point on or above the Earth's surface. In addition to military applications, the system is primarily used to gather spatial data needed for making maps and to calculate geographic positions for travelers on Earth who have GPS receivers. The system was originally called "NAVSTAR" (Navigation System with Timing And Ranging).