Geographic information systems (GIS) are used to store, manipulate, and analyze geospatial data. The end result of the analyzed data is usually displayed on a map. This guide lists some of the many GIS software programs and provides links to resources that are available to help you learn how to create your own maps. This guide also includes links to sources of data. This data can be attribute tables (which often can be downloaded as an Excel spreadsheet), shapefiles that tell the GIS how to draw the geographic boundaries you want to display, and aerial or satellite imagery.