Global Positioning System (GPS)

GPS is a passive, all-weather, 24-hour global navigation satellite system (GNSS) operated and maintained
by the Department of Defense (DoD), USA. It consists of a nominal constellation of 24 satellites in high altitude orbits.

Its primary mission is to provide passive, real-time, 3-D positioning, navigation and velocity data for land, air, and sea-based strategic and tactical forces operating anywhere in the world. A secondary--and most predominant--application is a wide range of civil positioning and time transfer.

Geographic Information System (GIS)

GIS is a geographic information system, is a collection of computer hardware, software, and geographic data for capturing,
storing, updating, manipulating, analyzing, and displaying all forms of geographically referenced information.