What is Wikimedia Commons?
The aim of Wikimedia Commons is to provide a media file repository "that makes available public domain and freely-licensed educational media content to all, and that acts as a common repository for the various projects of the Wikimedia Foundation."
Wikimedia Commons is a multilingual project. The default language for is English, but registered users can customize their interface to use any other available user interface translations. Many pages have also been translated into various languages. Users are encouraged to help with the translation.
Central media repository
Formerly each of the many Wikimedia projects—every single Wikipedia and Wiktionary, as well as Wikibooks, Wikisource, Wikinews, Wikiversity, and Wikiquote—used their own image namespace. There is no reliable way to reference images on other projects. Many good, free uploads on one wiki could go unnoticed on another. Thus, there was needless duplication of intellectual and creative work as well as unnecessary redundancy and increased maintenance.
For home page of this project, please see commons.wikimedia.org for more details.