The English version of Wikipedia , aka the free encyclopedia, currently has over 482,320 articles. That is over 100 times the number of articles in Microsoft's Encarta and 4 times the most complete edition of EncyclopÃ¦dia Britannica with 120,000 articles. I always liked Wikipedia - not just because it is free and allows the
public to view, use and even edit the content - but because every article is edited by people who know so much about the subject. For example computer science stuff are written by experts and they are so detailed I once used Wikipedia instead of my textbook! Or if you want to learn about a country you will get the information from people of that country, not some so called experts who have never even been there. Plus the stuff are up-to-date, in fact there is a news section.
Wikipedia is available in many languages, some with over 100,000 articles. The Farsi (Persian) version has over 5,600 pages but mostly stubs (small articles with very little information created for future editing).
Just in case you're new to the idea, Wiki is a database that allow the public to post and edit the information. Wikipedia is more than just an encyclopedia and if you still haven't heard of it you've got to check it out!
Update: (Octoboer 25) Exactly 8 months later, I rechecked the number of articles and the English version is almost doubled to over 787,000 (that's more than 6 times the most complete Britannica), of course the number of articles in Encarta and others doesn't change. Plus more specialized siblings to Wikipedia (such as Wikitravel) are created.