Global Positioning System

A system of satellites in low Earth orbit that, in conjunction with a receiver, can be used to determine one's location anywhere in the world with an accuracy of about 10 feet. Originally developed for US military use and deliberately scrambled to prevent other users from obtaining accuracy better than 150 feet, the scrambling was discontinued during the Clinton administration -- and the game of geocaching was founded the following day. While early GPS receivers only told users what their latitude, longitude, and elevation were, modern units have built-in road maps, voice commands, and various other features. And *all* cell phones are now required to have GPS built in so that 911 operators can determine where distress calls are originating.