GIS stands for Geographic Information Systems. The main software package is called ArcGIS and is supplied by the Environmental Systems Research Institute (ESRI). A good place to start learning more about the potential applications of GIS in demography and the social sciences is ESRI’s home page. In addition, you can find a staggering amount of information about GIS on the Internet, including software training and tutorials, data products, statistical techniques, and myriad areas of application (crime, health, planning, etc.).