The document provides an introduction to geographic information systems (GIS) including: - A definition of GIS as an integrated system that combines geographic and tabular data using software for analysis and presentation of that analysis in map form. - A brief history of early GIS maps including John Snow's 1855 cholera map, one of the first epidemiological maps. - An overview of current applications of GIS including 3D modeling, web-based GIS, and a wide range of uses in fields such as urban planning, environmental science, business, health care, and more. - A quote from GIS pioneer Jack Dangermond that the applications of GIS are limited only by users' imaginations