Wikipedia is an online free-content encyclopedia project helping to create a world in which everyone can freely share in the sum of all knowledge. It is supported by the Wikimedia Foundation and based on a model of openly editable content. The name "Wikipedia" is a blending of the words wiki (a technology for creating collaborative websites, from the Hawaiian word wiki, meaning "quick") and encyclopedia. Wikipedia's articles provide links designed to guide the user to related pages with additional information.

Wikipedia is written collaboratively by largely anonymous volunteers who write without pay. Anyone with internet access can write and make changes to Wikipedia articles, except in limited cases where editing is restricted to prevent disruption or vandalism.

Since its creation on January 15, 2001, Wikipedia has grown into the world's largest reference website, attracting 1.7 billion unique visitors monthly as of November 2020. It currently has more than 55 million articles in more than 300 languages, including 6,207,631 articles in English with 132,722 active contributors in the past month.