The Global Positioning System (GPS) revolutionized positioning on Earth, providing precise location data through satellite ranging. The GPS system was developed in 1978 by the U.S. Department of Defense  for military use, and it became available for civilian applications in 1983, transforming fields including navigation, fleet management, and time synchronization for telecommunications systems.

GPS consists of satellites in medium Earth orbit, about 20,200 kilometers above the surface, completing an orbit every 11 hours and 58 minutes. A fully operational constellation of 24 satellites, established in 1994, ensures global coverage. Ground support includes monitoring stations that track and adjust satellite positions to maintain accuracy against gravitational and solar influences.

As part of the Global Navigation Satellite System (GNSS), GPS integrates with systems like Russia’s GLONASS, Europe’s Galileo, and China’s BeiDou. This collaboration improves coverage, offers redundancy, and enhances accuracy in challenging environments.

Initially designed for military applications, GPS supports secure navigation for aircraft, ships, land vehicles, missile guidance, and search-and-rescue operations. It enables efficient surveying for land and construction, eliminating line-of-sight limitations and reducing survey time. Tasks that once took weeks can now be completed in a day. Public applications of GPS include navigation, fleet management, recreation, and critical services like time synchronization for banking and telecommunications.

GPS positioning relies on satellite ranging, measuring the time that radio signals travel from satellite to receiver. Distances are calculated using the time delay of signals traveling at the speed of light. At least three satellites determine a position, with a fourth to correct timing errors. Atomic clocks, accurate to a billionth of a second, ensure that the GPS system provides reliable, cost-effective positioning for diverse global applications.