Use this tag when referring to the R package for high level data visualization and mapping.
ggplot2 is a package for the open-source statistical programming language R, based upon the principles of the "Grammar of Graphics". Its strength lies in data exploration through visualization, particularly of large datasets. Its creator is Hadley Wickham, and it is actively maintained.
ggplot2 is becoming increasingly popular for mapping and spatial data visualization. ggmap is a relevant related R package that extends ggplot2 and includes functions for geocoding and the easy retrieval of basemaps from Google Maps, OpenStreetMaps, Stamen Maps, or CloudMade Maps.
Link to documentation - http://docs.ggplot2.org/current/