Quantum GIS (QGIS) is an open source Geographic Information System (GIS) that implements a large number of geospatial data access, visualization, processing, and analysis functions. It can access vector data stored in a wide variety of formats, including file-based (e.g. ESRI Shape Files, KML, GML), geodatabases (e.g. PostgreSQL/PostGIs, ODBC, ESRI Personal GeoDatabase, SQLlite), and network protocols (OPeNDAP, GeoJSON); raster data in one of over 40 formats supported by the underlying GDAL raster library (including NetCDF, HDF5, GeoTIFF, GRIB, and JPEG-2000); and Open Geospatial Consortium visualization and data access services (Web Map and Web Feature Services [WMS and WFS, respectively]). Depending upon the host system configuration, QGIS can also act as an alternative Graphical User Interface for the large collection of GRASS GIS geospatial processing functions. QGIS includes a "plug-in" architecture in which extensions to the core functionality of the application may be developed and used, with current plug-ins including support for GPS integration, interaction with the OpenStreetMap data servers, and data transformation tools.