Wikipedia [ c ] is a free-content online encyclopedia written and maintained by a community of volunteers , known as Wikipedians , through open collaboration and the wiki software MediaWiki. Wikipedia is the largest and most-read reference work in history, [ 3 ] [ 4 ] and is consistently ranked among the ten most visited websites ; as of December [update] , it was ranked fifth by Semrush , [ 5 ] and seventh by Similarweb.
Initially only available in English, Wikipedia now exists in more than languages. The English Wikipedia , with over 6. Wikipedia has been praised for its enablement of the democratization of knowledge , extent of coverage, unique structure, and culture. Wikipedia has been censored by some national governments, ranging from specific pages to the entire site.
Various collaborative online encyclopedias were attempted before the start of Wikipedia, but with limited success. Wikipedia was launched on January 15, [ 20 ] referred to as Wikipedia Day as a single English-language edition at www. Otherwise, there were initially relatively few rules, and it operated independently of Nupedia. Wikipedia gained early contributors from Nupedia, Slashdot postings, and web search engine indexing.
Language editions were created beginning in March , with a total of in use by the end of The English Wikipedia passed the mark of 2 million articles on September 9, , making it the largest encyclopedia ever assembled, surpassing the Yongle Encyclopedia made in China during the Ming dynasty in , which had held the record for almost years.
Citing fears of commercial advertising and lack of control, users of the Spanish Wikipedia forked from Wikipedia to create Enciclopedia Libre in February After an early period of exponential growth, [ 28 ] the growth rate of the English Wikipedia in terms of the numbers of new articles and of editors, appears to have peaked around early Around 1, articles were added daily to the encyclopedia in ; by that average was roughly In November , a researcher at the Rey Juan Carlos University in Madrid, Spain found that the English Wikipedia had lost 49, editors during the first three months of ; in comparison, it lost only 4, editors during the same period in In the same interview, he also claimed the number of editors was "stable and sustainable".
