Wikipedia is a free online encyclopedia written and maintained by volunteer editors, with millions of articles covering a broad range of subjects. Its English edition invites anyone to edit and offers content in multiple languages through separate Wikipedia sites. Readers can explore featured articles, current news, historical events, anniversaries, and selected images, while article archives provide access to earlier highlights. Wikipedia also supports participation through community spaces such as the Community portal, Village pump, Teahouse, Help desk, and Reference desk, where users can find resources, discuss the project, or ask questions.

Wikipedia is hosted by the Wikimedia Foundation, a nonprofit organization that also operates a family of volunteer projects. These include Wikimedia Commons for free media, Wikidata as a knowledge base, Wikibooks for textbooks and manuals, Wikisource for free-content texts, Wiktionary as a dictionary and thesaurus, and Wikivoyage as a travel guide. Other projects provide wiki software development, project coordination, quotations, species information, and learning tools.