Wikipedia began as a complementary project for Nupedia, a free online English-language encyclopedia project whose articles were written by experts and reviewed under a formal process. Nupedia was founded on March 9, 2000, under the ownership of Bomis, Inc, a web portal company. Its main figures were Jimmy Wales, Bomis CEO, and Larry Sanger, editor-in-chief for Nupedia and later Wikipedia. Nupedia was licensed initially under its own Nupedia Open Content License, switching to the GNU Free Documentation License before Wikipedia's founding at the urging of Richard Stallman.
Larry Sanger and Jimmy Wales founded Wikipedia. While Wales is credited with defining the goal of making a publicly editable encyclopedia, Sanger is usually credited with the strategy of using a wiki to reach that goal. On January 10, 2001, Larry Sanger proposed on the Nupedia mailing list to create a wiki as a "feeder" project for Nupedia. Wikipedia was formally launched on January 15, 2001, as a single English-language edition at www.wikipedia.com, and announced by Sanger on the Nupedia mailing list. Wikipedia's policy of "neutral point-of-view" was codified in its initial months, and was similar to Nupedia's earlier "nonbiased" policy. Otherwise, there were relatively few rules initially and Wikipedia operated independently of Nupedia.
Wikipedia gained early contributors from Nupedia, Slashdot postings, and web search engine indexing. It grew to approximately 20,000 articles and 18 language editions by the end of 2001. By late 2002, it had reached 26 language editions, 46 by the end of 2003, and 161 by the final days of 2004. Nupedia and Wikipedia coexisted until the former's servers were taken down permanently in 2003, and its text was incorporated into Wikipedia. English Wikipedia passed the 2 million-article mark on September 9, 2007, making it the largest encyclopedia ever assembled, eclipsing even the Yongle Encyclopedia (1407), which had held the record for exactly 600 years.