Geographic Information System. An organized collection of computer
hardware, software, geographic data, and personnel designed to
efficiently capture, store, update, manipulate, analyze, and display all
forms of geographically referenced information. GIS uses computer
software to link geographic information (where things are) with
descriptive information (what things are), unlike a flat paper map,
where "what you see is what you get," a GIS can present many layers of
different information (ESRI).