GIS Glossary - A Glossary of selected terms relevant to Geographic Information Systems. In .pdf format, viewable in Adobe's Acrobat Reader.  Click to view in browser or Right-Click to download the file and save locally. 

USGS "What is GIS" Web Site - an excellent, objective, comprehensive, and very readable introduction to GIS.

Map Cruizin.Com - another educational web site.  Besides useful instruction, his site includes useful information and a tutorial using software you can download for free.

GIS.com - A comprehensive source of information and advice on all aspects of geographic information systems (GIS). Learn what GIS is and can do for you, try it for yourself, find resources for building a GIS, and get the latest news affecting the GIS industry.