Global positioning systems (GPS) use satellites to connect with GPS devices and determine their location. Receivers in the devices connect with four or more satellites in the atmosphere and use the distance from the satellites to find the precise location
GPS is a network of several satellites that was originally developed by the United States military. These satellites continually orbit the Earth and transmit radio signals that receivers in devices can pick up. A receiver can tell how far away a satellite is based on these signals by using the time it took to receive the signal to determine the distance. At any given time, a GPS device that contains a receiver can connect with at least four satellites to determine its location anywhere on the planet.
When a GPS receiver connects with the satellites, it calculates its distance from each satellite and then determines the radius around each satellite location based on the distance measurements. The overlap between the spheres pinpoints the exact location. This process is known as "trilateration." Connecting with more satellites helps improve the receiver's accuracy. Although anyone with a GPS device can access GPS satellites free of charge, the United States owns the system.