Precise, satellite-based navigation and location system developed for U.S. military use but available to the general public with the use of proper equipment.
GPS is a fleet of more than 24 communications satellites that transmit signals globally around the clock. With a GPS receiver one can quickly and accurately determine the latitude, longitude, and in most cases the altitude of a point on or above the Earth's surface. A single GPS receiver can find its own position in seconds from GPS satellite signals, to an accuracy of 10 meters; accuracy within one meter can be achieved with sophisticated military-specification receivers. This capability has reduced the cost of acquiring spatial data for making maps while increasing cartographic accuracy. Other applications include measuring the movement of polar ice sheets, or even finding the best auto route between given points.