Geographic Resources Analysis Support System (commonly termed GRASS GIS) is a geographic information system (GIS) software suite used for geospatial data management and analysis, image processing, producing graphics and maps, spatial and temporal modeling, and visualizing.

The environment has a state that includes parameters such as the geographic region covered and the map projection in use.

All GRASS modules read this state and additionally are given specific parameters (such as input and output maps, or values to use in a computation) when executed.

GRASS has been under continuous development since 1982[3] and has involved a large number of federal US agencies, universities, and private companies.

The development of GRASS was started by the USA-CERL to meet the need of the United States military for software for land management and environmental planning.

USA-CERL officially ceased its involvement in GRASS after release 4.1 (1995), though development had been limited to minor patches since 1993.

In 1998, Markus Neteler, the current project leader, announced the release of GRASS 4.2.1, which offered major improvements including a new graphical user interface.

[4] Since then, GRASS has evolved into a powerful software suite with a wide range of applications in many different areas of scientific research and engineering.

[5][6][7] As of 2015, GRASS is used in academic and commercial settings around the world, and in many government agencies including NASA, NOAA, USDA, DLR, CSIRO, the National Park Service, the U.S. Census Bureau, USGS, and many environmental consulting companies.