A database system is an essential component of a geographic information system (GIS). GIS are driven off databases. Almost all entities in the world are tied to some geographical location, expressed by x (longitude) and y (latitude) coordinates. These entities are stored in GIS as a series of points, lines, and polygons.

The power of a GIS is its ability to store the coordinate information; however, most GIS have the ability to connect to other information stored in a database management system (DBMS). For example, usually one land parcel within a city is more than likely owned by one person; however, if that land parcel is located in Manhattan, with the dollar value of it being 20 million, more often than not that land parcel is ...