Global Positioning System (GPS)
From The Glossary of Digital Photography
A navigational system based on at least 24 satellites that transmit signals continuously. Various types of receivers, including small hand-held units, are used to receive the signals and tell the user exactly where he or she is. The official name is Navigation Signal Timing and Ranging Global Positioning System, or NAVSTAR GPS for short. The system was set up and is maintained by the US Department of Defense. There are two versions of the system: a civilian and a military version. The civilian version is accurate to within +/- 15 meters, while the military version has error corrections built-in to make it much more accurate. Some digital cameras are now being built with a GPS input.
