GPS - (Global Positioning System) A satellite-based radio navigation system run by the U.S. Department of Defense. It was designed so that signals from at least four satellites would be on the horizon at all times, which is sufficient to compute the current latitude, longitude and elevation of a GPS receiver anywhere on earth to within a few meters. The first GPS satellite was launched in 1978. Now the navigation system consists of 24 satellites that hover 12,500 miles above earth and travel 10,000 mph. They can orbit the earth in as little as 12 hours.

To pinpoint the location of a receiver, GPS uses triangulation. This is the navigation technique used by ship captains for centuries, way before any electronic devices were invented. Because of this, there became a demand and now everyday people

The uses of GPS navigation are unlimited. Cars, trucks, motorcycles, bicycles, boats, jetski, ships, hikers, climbers, hunters, cell phones, airplanes, helicopters, paragliders, road construction, land surveyors, mapping, geographic information systems, farmers, machine guidance, and atomic clocks use this technology. One main feature of GPS receivers display information about location, speed, and direction.

GPS designed for automobiles display maps, nearby roads, restaurants and landmarks. Ships have a "man overboard" (MOB) system, which records the location when the person has gone overboard. GPS certified for planes and jets have an auto-pilot function that allow for completely automated en-route navigation. Climbers get lost and hikers get hurt. GPS provides a precise position and can greatly enhance the chance of rescue. Farmers use GPS to position crops exactly where they want them.