GIS stands for Geographic Information Services. What GIS does is combine geospatial features with tabular data in order to help users analyze real-world issues. GIS is more than just a pretty map, it can help users make intelligent decisions based on spatial data.
For example, developers may be searching for a parcel of land greater than 20 acres, that is adjacent to a railroad track, that has good soil for septic systems, and is accessible to a public water supply. By overlaying parcels, soils, water lines and aerial photography properties that meet the criteria can be graphically displayed. GIS uses a relational database to perform analysis on each map layer. Using the combination of map layers and databases, GIS can perform extensive spatial and statistical methods for analyzing data. View an image showing how GIS works.