Geographical Information Systems (GIS) are computer programs for the capture, management, analysis and display of spatially referenced data. They are now increasingly widely used in ecology and environmental management, both in the organisation and analysis of pre-existing data sets and for analysis of data collected during fieldwork. This module aims to introduce their basic principles, capabilities, applications and limitations. Only basic familiarity with a PC is required and there will be weekly practical classes using the ArcGIS software. The main emphasis will be on imparting an understanding of what a GIS is, the strengths and weaknesses of such systems, and their practical use in research contexts (including MSc dissertations).