Wikipedia is a free, open content online encyclopedia created through the collaborative effort of a community of users known as Wikipedians. Anyone registered on the site can create an article for publication; registration is not required to edit articles.

In practice, any person who has access to the World Wide Web may read the content of Wikipedia on the website wikipedia.org without paying any money. This, however, does not mean that Wikipedia content is fully non-commercial. Copies of Wikipedia content can be sold.

The name was suggested by Sanger on 11 January 2001 as a portmanteau of the words wiki (Hawaiian for "quick") and encyclopedia. The wikipedia.com and wikipedia.org domain names were registered on 12 and 13 January, respectively, with wikipedia.org being brought online on the same day.

Wikipedia's purpose is to benefit readers by presenting information on all branches of knowledge. Hosted by the Wikimedia Foundation, it consists of freely editable content, whose articles also have numerous links to guide readers towards more information.