Wikipedia is a free online encyclopedia that anyone can edit in good faith, and tens of millions already have!

Wikipedia's purpose is to benefit readers by containing 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 to more information.

Written collaboratively by largely anonymous volunteers, anyone with Internet access and not blocked, 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 6,639,455 articles in English with 129,408 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, although editors do not need to be familiar with them 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 published sources. 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.

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, clear, and balanced 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 Researching with Wikipedia).