The document discusses geographic information systems (GIS). It defines GIS as a computer system for collecting, storing, analyzing and displaying spatially-referenced data. The key components of a GIS are hardware, software, data, procedures and users. GIS has functions like inputting, storing, querying, analyzing and displaying spatial data. It can be used for applications in various fields such as agriculture, transportation and environmental planning. The document also covers spatial data models, coordinate systems and map projections used in GIS.