Wikipedia is a free encyclopedia hosted by the non-profit Wikimedia Foundation, which operates several other multilingual and free-content projects:

Wiktionary
Dictionary and thesaurus
Wikibooks
Free textbooks and manuals
Wikiquote
Collection of quotations
Wikisource
Free source documents
Wikispecies
Directory of species
Wikinews
Free content news source
Commons
Shared media repository
Meta-Wiki
Wikimedia project coordination