WikiPedia – 5th Anniversary – January 15 writes “Wikipedia is written collaboratively by volunteers, allowing articles to be changed by anyone with access to a web browser. The project began on January 15, 2001 as a complement to the expert-written Nupedia and is now operated by the non-profit Wikimedia Foundation. Wikipedia has more than 3,100,000 articles, including more than 920,000 in the English-language version, and as of January 2006 it has more than 792,000 registered users.