Wikipedia is a multilingual free online encyclopedia written and maintained by a community of volunteers, known as Wikipedians, through open collaboration and using a wiki-based editing system called MediaWiki. Wikipedia is the largest and most-read reference work in history. It is consistently one of the 10 most popular websites ranked by Similarweb and formerly Alexa; as of 2023, Wikipedia was ranked the 5th most popular site in the world. It is hosted by the Wikimedia Foundation, an American non-profit organization funded mainly through donations.
Wikipedia was launched by Jimmy Wales and Larry Sanger on January 15, 2001.