GPS (the Global Positioning System) is a worldwide radio-navigation system that uses satellites. It allows you to determine the exact location (latitude and longitude coordinates, altitude, etc.) of each object, equipped with a suitable receiver.
The system is based on the principle of triangulation, i.e. the measurement of the distance from three points (in this case the satellites) to specify the exact location, on the basis of the obtained results. A special device including a computer and a very precise clock is used for the calculation. In favourable circumstances, the device also receives the location of a fourth satellite, which increases the accuracy of the measurements (which are without this extremely accurate).
The system consists of artificial satellites(currently over 20) orbiting the Earth on different trajectories, at an approximate height of 20 200 km. The system, originally developed for military use, is operated from the United States. Today it is widely used in marine navigation, aviation, automotive and tourism.