Abstract: Definitions of what a Geographic Information System (GIS) is vary. In general, most definitions describe a GIS as capable of storing, analysing, and displaying spatially (or geographically) referenced data. Spatially referenced data can be stored in two ways inside a GIS: as vector data or raster data. Most GIS software can be categorised as either a raster- or vector-based GIS. This has become less apparent as many software packages work fluidly with either data format.