The Global Positioning System (GPS) is a worldwide radio-navigation system formed from a constellation of 24 orbiting satellites and their ground stations. Each satellite, in orbit 12,000 miles above the surface of the earth, transmits a constant stream of encoded data. This data contains information about the location of the satellite along with a highly accurate time code. The GPS satellites are monitored by five ground stations, based in Hawaii, Ascension Island, Diego Garcia, Kwajalein, and Colorado Springs, that ensure both their operational health and their exact position in space at all times.

For most users, the GPS receiver is the most important element of the GPS system. The GPS receiver gathers time and position data broadcasted from the network of satellites and converts it into useful location information. Recent advances in GPS circuitry and manufacturing technologies have resulted in ultra compact designs with integrated antenna that interface directly to handheld PDAs, making the technology accessible to the mass market at a fraction of what it used to cost.

The GPS receiver operates by building up an internal map of the precise location of up to 12 satellites. By applying a mathematical formula to the data received from each satellite, the GPS receiver can calculate its exact distance from each satellite. Once the receiver's distance from several satellites has been established, a process called "triangulation" can be applied to derive an exact location on the earth's surface. This information further allows altitude, speed and direction to be calculated with great precision. As a result, it is now possible to pinpoint one's exact location in real time onto a map of the surrounding area with the help of personal navigation software such as EasyNav that runs on virtually any handheld Pocket PC PDA.