Wikipedia (IPA: /ˌwiːkiːˈpiːdi.ə/ or /ˌwɪːkiːˈpiːdi.ə/) is a multilingual, Web-based, free content encyclopedia project. Wikipedia is written collaboratively by volunteers; with rare exceptions, its articles can be edited by anyone with access to the Web site. The name is a portmanteau of the words wiki (a type of collaborative website) and encyclopedia. Its primary servers are in Tampa, Florida, with additional servers in Amsterdam and Seoul.
Wikipedia was launched as the English Wikipedia on January 15, 2001, as a complement to Nupedia, an expert-written and now defunct encyclopedia. The project is now operated by the Wikimedia Foundation, a non-profit organization created by Jimmy Wales, and has over six million articles in 250 languages, including 1.6 million in the English edition. Wikipedia has steadily risen in popularity since its inception and currently ranks among the twelve most-visited websites worldwide.
Wikipedia's reliability and accuracy have been questioned. The site has also been criticized for its susceptibility to vandalism, uneven quality, systemic bias and inconsistencies, and for favouring consensus over credentials in its editorial process. Wikipedia's content policies and sub-projects set up by contributors seek to address these concerns. Scholarly studies have concluded that vandalism is generally short-lived, and that Wikipedia is roughly as accurate as other online encyclopedias.