Wikimedia Commons

The Wikimedia Commons (English homepage; also called "Commons" or "Wikicommons") is a repository of free content images, sound and other multimedia files. It is another project of the Wikimedia Foundation like Wikipedia, but one that is a common resource repository to all the various Wikimedia sister projects regardless of language.

Files uploaded to the Commons repository can be used like locally uploaded files on all other projects on the Wikimedia servers in all languages, including Wikipedia, Wikibooks, Wikisource and Wikinews, or indeed downloaded for offsite use, as all of the content is either in the public domain or released under free licenses such as the GNU Free Documentation License.

History
The project was proposed by Erik Möller in March 2004 and launched on September 7, 2004. a key motivation behind the setup of a central repository was a desire to reduce duplication of effort across the Wikimedia projects and languages, as the same file had to be uploaded to many different wikis separately before the Commons was created. The technical feature to use any file from the Commons on any Wikimedia project was implemented and enabled in October 2004, which led to rapid adoption of Commons as a repository. The project logo was created by Reid Beels, who had initially submitted it to a logo contest for Wikinews. It was entered into the Commons logo competition, which it won, and was officially adopted in November 2004.

In April 2005, Directmedia, a Berlin company which also publishes a German language edition of Wikipedia on DVD, donated a collection of 10,000 reproductions of public domain paintings to Wikimedia Commons, which were uploaded together with metadata about the art and its creators.

On May 24, 2005, Wikimedia Commons reached a milestone of 100,000 uploaded media files (excluding thousands of weather and market data images for Wikinews). It also received an honorary mention at the 2005 Prix Ars Electronica awards in May 2005.

Over time, additional functionality has been developed to interface Wikimedia Commons with the Wikimedia projects. Daniel Kinzler (known in the Commons community as "Duesentrieb") wrote applications for finding appropriate categories for uploaded files ("CommonSense"), determining the usage of files across the Wikimedia projects ("CheckUsage"), locating images with missing copyright information ("UntaggedImages"), and relaying information about administrative actions such as deletions to the relevant wikis ("CommonsTicker"). Lack of cross-project communications has sometimes caused friction within the Wikimedia community, and many recent development efforts have focused on improving communications and decision-making processes.

Specialized uploading tools and scripts such as "Commonist" have been created to simplify the process of uploading large numbers of files. In order to review free content photos uploaded to Flickr, users can participate in a collaborative external review process ("FlickrLickr"), which has resulted in more than 5,000 uploads to Commons.

Policies and usage
Most Wikimedia projects still allow local uploads which are not visible to other projects or languages, but this option is meant to be used primarily for material which local project policies allow, but which would not be permitted according to the copyright policy of the Commons, such as fair use content. Wikimedia Commons itself does not allow fair use or uploads under non-free licenses, including licenses which restrict commercial use of materials or disallow derivative works. Licenses that are acceptable include the GNU Free Documentation License, Creative Commons Attribution and ShareAlike licenses, and the public domain.

Given its primary function as a supporting project for the other Wikimedia web sites, the main content policy for files uploaded to the Commons is that they must be potentially useful on any of the Wikimedia projects. This excludes material such as purely personal pictures and artwork, in contrast to image sharing repositories like Flickr, Facebook and DeviantART. Nevertheless, large numbers of files hosted on the Commons are not used directly on any Wikimedia project and likely never will be; as such, the project has grown into a repository of multimedia in its own right, which is frequently linked to from articles on Wikipedia and other Wikimedia websites to provide supplemental materials.

The default language for the Commons is English, but registered users can customize their interface to use any other available user interface translations. Many content pages, in particular policy pages and portals, have also been translated into various languages. Files on the Wikimedia Commons are categorized using MediaWiki's category system. In addition, they are often collected on individual topical gallery pages. While the project was originally proposed to also contain free text files, these continue to be hosted on a sister project, Wikisource.