A Geographical Information System (GIS) has recently been developed for the assessment of the agricultural potential of the Southern African Development Community (SADC) region. The main value of this GIS is the integration of agricultural resource information from the SADC countries in order to support regional planning. The development of GIS technology makes it possible to compile, store, retrieve, analyse and display vast quantities of spatial data on, inter alia, the climate, topography, soils and infrastructure of the region. This article aims to give background information on the nature and general application of a GIS. Attention is given to the capabilities of a GIS, the spatial questions that drive analyses, basic database requirements, analytical and operational functions, as well as the applications of a GIS in land reform. More detail on the spatial agricultural resource data captured and its use by means of the SADC GIS will be described in a later article.