QGIS is a free open-source and user friendly desktop geographic information system application that provides data viewing, editing, and analysis. As a free software application under the GNU GPL, it can be freely modified to perform different or more specialized tasks.
What it does is, it 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.
The program has a lot of documentation in English but some documents, such as the user guide, are also available in other languages.