“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.” Jimmy Wales

Wikipedia is an encyclopedia that anyone can edit, and tens of millions already have!

Wikipedia's purpose is to benefit readers by acting as a widely accessible and free encyclopedia that contains information on all branches of knowledge. Hosted by the Wikimedia Foundation, Wikipedia consists of freely editable content, whose articles also have numerous links to guide readers for more information.

Written collaboratively by largely anonymous volunteers, anyone with Internet access and in good standing can write and make changes to Wikipedia articles (except in limited cases where editing is restricted to prevent disruption or vandalism). Since its creation on January 15, 2001, Wikipedia has grown into the world's largest reference website, attracting over a billion visitors monthly. It currently has more than sixty million articles in more than 300 languages, including 6,611,785 articles in English with 130,218 active contributors in the past month.

The fundamental principles of Wikipedia are summarized in its five pillars. The Wikipedia community has developed many policies and guidelines, but you don't need to be familiar with them all before contributing.

Anyone can edit Wikipedia's text, references, and images. What is written is more important than who writes it. The content must conform with Wikipedia's policies, including being verifiable by a published reliable source. Editors' opinions, beliefs, personal experiences, unreviewed research, libelous material, and copyright violations will not remain. Wikipedia's software allows easy reversal of errors, and experienced editors watch and patrol bad edits. Begin by simply clicking the Edit button at the top of any non-protected page.

Wikipedia differs from printed references in important ways. It is continually created and updated, and encyclopedic articles on new events appear within minutes rather than months or years. Because anyone can improve Wikipedia, it has become more comprehensive than any other encyclopedia. Its contributors improve the quality and quantity of the articles as well as remove misinformation, errors, and vandalism. Any reader can fix a mistake or add more information to articles (see Wikipedia:Researching with Wikipedia).

Over time, Wikipedia's pages tend to become more detailed and balanced. Wikipedia has tested the wisdom of the crowd since 2001 and found that it succeeds. As Linus's law asserts, "Given enough eyeballs, all bugs are shallow!"