GPS stands for Global Positioning System.
It’s a satellite-based system allowing to know precisely the position of a receiver on the surface of the Earth.
The receiver indicates its position in Longitude, Latitude and elevation, with an accuracy of a few meters for basic systems, a few cm (or better) with high-end systems. This technology can be considered a major technological evolution in the technique of mapping. It is now possible to accurately determine the absolute position of objects with cheap and easy-to-use equipment, while the same required complex, heavy, expensive and difficult to use topographic surveying equipment.