What date is celebrated as Wikipedia Day?

Wikipedia Day is celebrated on January 15, marking the launch of Wikipedia in 2001. The first recovered edit to the new English-language site was made on January 15, and the project formally opened that day.

Wikipedia began as a companion project to Nupedia, an online encyclopedia whose articles were expected to pass through a lengthy expert-review process. Jimmy Wales and Larry Sanger launched Wikipedia as a faster, collaborative place where drafts could be created and improved publicly. The name combines “wiki,” a Hawaiian word associated with speed, and “encyclopedia.”

The project initially operated at Wikipedia.com and was hosted using donated resources associated with Bomis. It quickly attracted contributors from Nupedia, online communities, and search-engine users. Other language editions began appearing later in 2001, including German, Catalan, French, Swedish, and Italian.

Wikipedia Day is sometimes confused with the date of the domain registrations, which occurred shortly before launch. The anniversary refers to the project's opening and first recorded activity, not simply to the registration of its web address.