The term ‘Geographic Information Systems’ (GIS) defines those computerised systems designed to gather, store, manage, visualise and analyse data with a spatial component. While GIS is generally used to refer to software applications created to manage geographic information, in truth GIS are also defined by other key components such as the spatial data being analysed, the hardware and the human component defined by users' training, experience and decisions. All these are key parts of what is known as GIS, and it is why many argue that GIS should be described in terms of a conceptual and methodological framework rather than software in isolation. This chapter introduces the historical development of GIS and presents an overview of key concepts, approaches for geovisualisation and spatial analysis techniques in GIS. It summarises areas of application and available GIS software, and concludes with some final thoughts on the future of GIS.