WikipediaWikipedia (i/ˌwɪkɨˈpiːdiə/ or i/ˌwɪkiˈpiːdiə/ WIK-i-PEE-dee-ə) is a free-access, free-content Internet encyclopedia, supported and hosted by the non-profit Wikimedia Foundation. Those who can access the site can edit most of its articles, with the expectation that they follow the website's policies. Wikipedia is ranked among the ten most popular websites and constitutes the Internet's largest and most popular general reference work.
Jimmy Wales and Larry Sanger launched Wikipedia on January 15, 2001. Sanger coined its name, a portmanteau of wiki] and encyclopedia. Initially only in English, Wikipedia quickly became multilingual as it developed similar versions in other languages, which differ in content and in editing practices. The English Wikipedia is now one of more than 200 Wikipedias and is the largest with over 4.9 million articles. There is a grand total, including all Wikipedias, of nearly 35 million articles in 288 different languages. As of February 2014, it had 18 billion page views and nearly 500 million unique visitors each month. Globally, Wikipedia had more than 25 million accounts, out of which there were about 72,000 active editors as of May 2015. Supporters of Wikipedia cite a 2005 survey of Wikipedia published in Nature based on a comparison of 42 science articles with Encyclopædia Britannica, which found that Wikipedia's level of accuracy approached Encyclopædia Britannica 's. Criticisms of Wikipedia include claims that it exhibits systemic bias, presents a mixture of "truths, half truths, and some falsehoods", and is subject to manipulation and spin.