A Geographic Information System (GIS) called the Spatial ANalysis System (SPANS) has been in use in the Geology Section of the Applied Geoscience Branch since 1990 September. The background for the operation and application of a GIS is discussed, and the specific introduction and setup of SPANS in the Geology Section are provided in detail. The major components of SPANS, including raster, vector and quadtree data structures, data input, classifications, interpolations, and other operational procedures are described. This introduction draws examples from the literature, from work done by the Geology Section, and from the SPANS manuals. This report does not cover all the capabilities of SPANS, but is intended as an introduction to the operation of such a system.