The Global Positioning System (GPS) is a U.S. space-based radio navigation system that provides reliable positioning, navigation, and timing services to civilian users on a continuous worldwide basis -- freely available to all. For anyone with a GPS receiver, the system will provide location and time. GPS provides accurate location and time information for an unlimited number of people in all weather, day and night, anywhere in the world. The GPS is made up of three parts: satellites orbiting the Earth; control and monitoring stations on Earth; and the GPS receivers owned by users. GPS satellites broadcast signals from space that are picked up and identified by GPS receivers. Each GPS receiver then provides three-dimensional location (latitude, longitude, and altitude) plus the time.
Differential Global Positioning System (DGPS). This is an enhancement to Global Positioning System that uses a network of fixed, ground based reference stations to broadcast the difference between the positions indicated by the satellite system and the known fixed positions. This system is used only by us the middle India. Except all this types of Geological tools we use latest version of geological software's like Map Info, Auto Cad, Map source, GIS & GPS etc. We prepare Maps & Plans in above software's .And we also use the internet tool i.e.-Google earth (Bhuvan).