Encyclopedias

Wikipedia is a free, open content, community-built encyclopedia with thousands of articles on topics from A to Z. Available in dozens of languages.

A platform for user-generated knowledge. Knol encourages authors to write authoritative articles on specific subjects.

Online encyclopedia entries, dictionary definitions, and thesaurus help from Infoplease, covering topics from astrophysics to Zimbabwe.

Official site of the Encyclopedia Britannica, one of the world's best-known reference books. Find short encyclopedia entries and definitions, or register for complete access.