GIS applications have a heavily customised terminology, and publications relating to the subject sometimes have a tendency to lean toward the indiscriminate use of complex terms and abbreviations so similar in nature that even those with much experience in the subject can be left scratching their heads in confusion. This is further exacerbated by the fact that the topic is essentially a combination of cartographic, computing, and statistical principles all of which have their own heavily jargonised means of expression. It has been noted that discussions regarding GIS, irrespective of discipline, tend to be off putting for people with little prior exposure to the subject, and these highly specialised terms no doubt have much to do with that. Nevertheless, they are a necessary component of the discipline and should be both understood and used correctly. A brief description of some of the main terms used in this module can be found below. For a more complete reference of terminology, the book A to Z GIS: an illustrated dictionary of geographic information systems (Wade & Sommer 2001) is a useful starting point. Conolly & Lake (2006) contains a glossary of GIS terms with an archaeological perspective.