Geographic Information Systems (GIS) are computer tools that use science and technology that are utilized to capture, store, manage, map, query and analyze large quantities of data, which is then applied to one map. Since GIS offers the ability to layer information, one map can offer many kinds of data. With this tool, users are able to easily identify and analyze patterns and relationships.
Although many agencies benefit from the use of Geographic Information Systems, one example of its use is in law enforcement. Crime analysts use GIS for crime mapping. Crimes such as burglary, assault, vandalism, theft are plotted (or data captured) onto a map as they occur. Using this information, the crime analyst is then able to visually identify trends surrounding the particular crimes. Geographic Information Systems may help to formulate crime fighting strategies, procure resources, or even prevent future crimes using the data trends.
Other agencies or industries that are aided by the use of Geographic Information Systems are oil and gas industries, land surveyors, mining companies, and government municipalities. Two government entities that gain information from GIS are the Centers for Disease Control and Prevention (CDC) and the Environmental Protection Agency (EPA).
Sources:
http://www.nerrs.noaa.gov/doc/siteprofile/acebasin/html/gis_data/gisint2.htm
http://www.epa.gov/reg3esd1/data/gis.htm