The Wikimedia Foundation maintains and develops free-content, multiple-author projects and makes the contents available to the public free of charge. In addition to its encyclopedia, Wikipedia, there is a multi-language dictionary/thesaurus (Wiktionary), a collection of e-book resources for students such as textbooks and annotated public domain books (Wikibooks), and a repository for other forms of free media, Wikimedia Commons, that contains (as of 2009) over 4.5 million images, videos, and sound files. Read more about Wikimedia Foundation...