Global Positioning System uses a constellation of 24 satellites and their related ground stations to create a radio navigation system which is worldwide. The satellites are reference points which are used to calculate accurate positions of just about any location in the world.
GPS was originally developed by the U.S. Department of Defence in 1978 and was originally known by the name NAVSTAR (Navigation System with Timing and Ranging). By June of 1995 GPS was deemed fully operational. GPS is used by a wide variety of industries such as foresty, mining exploration, in addition to the military. GPS is now a publicly available service which can be used by anyone.
GPS can calculate the longitude and latitude of locations and transmit this information to a receiver which enables the person using GPS to correctly locate and travel to destinations.
GPS devices have been manufactured into some vehicle models and are also available as stand-alone devices, such as those manufactured by Garmin and other companies. There are also GPS programs and receivers avaialble for mobile devices such as PDAs, cell phones and laptops. Many mobile devices are already GPS capable and require only that a receiver be attached to work.
GPS devices are becoming more economical and are quite easy to use.