How does GPS determine your exact location?

GPS determines your location through a process called trilateration. Your GPS receiver picks up signals from multiple satellites orbiting Earth, each broadcasting its precise position and the exact time the signal was sent. By measuring how long each signal takes to arrive, the receiver calculates its distance from each satellite. With signals from at least four satellites, the receiver can pinpoint your exact location in three dimensions, including latitude, longitude, and altitude. The fourth satellite is needed to correct for tiny timing errors in the receiver's clock. The more satellites your device can detect, the more accurate the position fix becomes. Modern GPS can typically achieve accuracy within a few meters under open sky conditions.