QGIS (previously known as Quantum GIS) is a cross-platform free and open-source desktop geographic information system (GIS) application that provides data viewing, editing, and analysis
Similar to other software GIS systems, QGIS allows users to create maps with many layers using different map projections. Maps can be assembled in different formats and for different uses. QGIS allows maps to be composed of raster or vector layers. Typical for this kind of software, the vector data is stored as either point, line, or polygon-feature. Different kinds of raster images are supported, and the software can georeference images.
QGIS integrates with other open-source GIS packages, including PostGIS, GRASS, and MapServer to give users extensive functionality. Plugins written in Python or C++ extend QGIS’s capabilities. Plugins can geocode using the Google Geocoding API, perform geoprocessing using fTools, which are similar to the standard tools found in ArcGIS, and interface with PostgreSQL/PostGIS, SpatiaLite and MySQL databases.