Wikipedia was launched on January 15, 2001, by Jimmy Wales and Larry Sanger; Sanger coined its name as a portmanteau of "wiki" and "encyclopedia".^[7][8] Initially available only in English, versions in other languages were quickly developed. The English Wikipedia, with 6.3 million articles as of April 2021, is the largest of the 321 language editions. Combined, Wikipedia's editions comprise more than 56 million articles, and attract more than 17 million edits and more than 1.7 billion unique visitors per month.^[9][10]

Wikipedia has received praise for its enablement of democratization of knowledge, extent of coverage, unique structure, culture, and absence of commercial bias, but has also been criticized for its uneven accuracy and for exhibiting systemic bias, particularly gender bias against women, and ideological bias, particularly a left-wing political bias.^{[3][11][12][13][14][15]} In 2006, Time magazine stated that the open-door policy of allowing anyone to edit had made Wikipedia the "biggest and perhaps the best encyclopedia in the world", and a testament to the vision of Jimmy Wales.^[16] In 2018, Facebook and YouTube announced that they would help users detect fake news by suggesting links to related Wikipedia articles.^[17]