Qgis Development Team : Qgis 2.8 User Guide

QGIS is an Open Source Geographic Information System. QGIS currently runs on most Unix platforms, Windows, and OS X. QGIS is developed using the Qt toolkit and C++. This means that QGIS feels snappy and has a pleasing, easy-to-use graphical user interface (GUI). QGIS aims to be a user-friendly GIS, providing common functions and features. The initial goal of the project was to provide a GIS data viewer. QGIS has reached the point in its evolution where it is being used by many for their daily GIS data-viewing needs. QGIS supports a number of raster and vector data formats, with new format support easily added using the plugin architecture.