GPS navigation systems are satellite navigation systems that connect systems on Earth, such as computers and car navigation devices, with satellites in space. The GPS, or Global Positioning System, operates using 24 satellites that connect with receivers in points around the world. The GPS system began as an initiative by the United States government, but now sees widespread use among citizens.
GPS devices work by coordinating signals between receivers on Earth and orbital satellites. Satellites identify and track systems on Earth, then provide information on users' locations in real time, operating around the clock. Some GPS systems operate as one-way signals, receiving only information from satellites, while others use information from satellites to communicate with other GPS units. Upon receiving satellite signals, GPS units determine the time and their location on the Earth's surface, which reads as latitude and longitude.
Although GPS units operate in the same basic manner, they come in many varieties. GPS systems vary in complexity and sophistication; some work with computer systems while others come in small portable units for cars. Although operating as a cohesive unit, the GPS system contains three distinct parts: space, control and user. The space segment involves technical operation of satellites by space agencies. The control branch involves the military and scientists keeping orbits in the atmosphere and guiding them through space while the user segment includes devices that receive satellites' information.