On Sept. 9, 2007, the English version of Wikipedia catalogued more than 2 million articles, making it the largest encyclopedia in history. The Wikipedia Foundation is based in San Francisco, California.

Wikipedia is online-only and free to use. Anyone can use information found in its entries, if they follow certain rules. “Imagine a world in which every single person on the planet is given free access to the sum of all human knowledge. That's what we're doing,” says founder Jimmy Wales.

Wikipedia is managed by a dedicated group of editors, who write, edit and update its encyclopedic entries. The project has also evolved into a fairly reliable source of information—a 2005 study by the journal Nature compared it favorably to Encyclopaedia Britannica.

catalog
Verb

to list or order by type.

editor
Noun

person who regulates and manages the language and concepts of a publication.

encyclopedia
Noun

book, set of books, or set of articles offering introductory or comprehensive information on a branch of knowledge or a particular subject.

journal
Noun

record of events, updated regularly.

reliable
Adjective

dependable or consistent.

Wikipedia
Noun

free, multi-lingual Internet encyclopedia written and edited entirely by volunteers.