Wikipedia is a free online encyclopedia created and edited by volunteers around the world. Hosted by the nonprofit Wikimedia Foundation, it provides open access to a broad, multilingual collection of knowledge, with millions of articles in English and many other languages. Its community-driven model brings together contributors to develop and maintain information for readers worldwide.

Wikipedia is part of a wider family of free knowledge projects hosted by the Wikimedia Foundation. These include Wikimedia Commons, a collection of free media; Wikivoyage, a travel guide; Wiktionary, a dictionary; Wikibooks, a source of free textbooks; Wikidata, a knowledge base; Wikiversity, a learning resource; Wikiquote, a collection of quotations; Wikisource, a library of free content; Wikispecies, a directory of species; and Wikifunctions, a function library. The foundation also supports MediaWiki, free wiki software, and Meta-Wiki for community coordination and documentation.

Readers can use the official Wikipedia app on Android and iOS to save articles for offline reading, sync reading lists across devices, and customize their reading experience.