Geographic Information Systems (GIS) can be used to display spatial data and to solve problems that involve spatial factors. GIS is particularly useful for relating, integrating, and analyzing information from these different themes (or layers) of spatial information. Therefore, anything that can be placed on a map is a candidate for GIS, and so the variety of uses are quite extensive.
Common uses of GIS include inventory and management of resources, crime mapping, establishing and monitoring routes, managing networks, monitoring and managing vehicles, managing properties, locating and targeting customers, locating properties that match specific criteria and managing agricultural crop data, addressing public health concerns, mapping wildfire risk and preparedness, modeling hazmat risk, first response, and mapping/monitoring/mitigating invasive species.
This is only a beginning!