Geographic Information System: a system of software, hardware and data used to represent and analyze information about spatial locations and relationships. For example, municipalities use GIS to map infrastructure such as parcel and district boundaries, roads, parks, water and sewer lines, and keep up-to-date information about them like maintenance schedules, property ownership and tax data. A database is used to contain and organize the data, such as the physical location and extent of services and associated attributes (e.g., type of road, sizes of pipes, land-use). Visual representations (maps) of a municipality's data can be produced by layering. Typically, one layer may show the physical geography of the area, another the district boundaries, another the parcel boundaries. Yet other layers may show the locations of buildings labeled with the name of the property owner, the locations of sewer, water, or electrical services, emergency services or schools. Still other layers might the distribution of crimes or  flooding. Maps can be produced to help decision-makers analyze the municipality's resources, allocate funds to projects or to inform zoning changes. Interactive maps on the web, such as MapQuest™, are usually the product of GIS.

A wide variety of academic disciplines use GIS to investigate physical and social processes. For example, a geologist might use GIS to map and analyze tectonic data, or geological units. An environmental scientist might use GIS to track soil erosion in a watershed or pollution sources. Archaeologists commonly use GIS to study artefactual and geological data from sites in local and regional contexts. Sociologists, political scientists, and historians use GIS to examine spatial and temporal trends in social phenomena like poverty, environmental discrimination, voting patterns, and diasporae.

Wesleyan University licenses ESRI's ArcGIS as the campus GIS solution. It is used by numerous faculty and students in research and teaching, and by Physical Plant in the administration of the campus physical environment. For more extensive information about GIS, including many illustrations and examples, see the ESRI GIS site http://www.gis.com.