This page is an introduction for visitors to the Wikipedia project. There is also an encyclopedia article about the topic: Wikipedia.
Wikipedia (pronounced) is a multilingual, Web-based, free-content encyclopedia project based mostly on anonymous contributions. The name "Wikipedia" is a portmanteau of the words wiki (a type of collaborative Web site) and encyclopedia. Wikipedia's articles provide links to guide the user to related pages with additional information.

Wikipedia is written collaboratively by an international (and mostly anonymous) group of volunteers. Anyone with internet access can write and make changes to Wikipedia articles. There are no requirements to provide one's real name when contributing; rather, each writer's privacy is protected unless they choose to reveal their identity themselves. Since its creation in 2001, Wikipedia has grown rapidly into one of the largest reference web sites, attracting around 65 million visitors monthly as of 2009. There are more than 75,000 active contributors working on more than 13,000,000 articles in more than 260 languages. As of today, there are 3,028,289 articles in English. Every day, hundreds of thousands of visitors from around the world collectively make tens of thousands of edits and create thousands of new articles to augment the knowledge held by the Wikipedia encyclopedia. (See also: Wikipedia:Statistics.)

Visitors do not need specialized qualifications to contribute. Wikipedia's intent is to have articles that cover existing knowledge, not create new knowledge (original research). This means that people of all ages and cultural and social backgrounds can write Wikipedia articles. Most of the articles can be edited by anyone with access to the Internet, simply by clicking the edit this page link. Anyone is welcome to add information, cross-references, or citations, as long as they do so within Wikipedia's editing policies and to an appropriate standard. Substandard or disputed information is subject to removal. Users need not worry about accidentally damaging Wikipedia when adding or improving information, as other editors are always around to advise or correct obvious errors, and Wikipedia's software is carefully designed to allow easy reversal of editorial mistakes.

Because Wikipedia is an ongoing work to which, in principle, anybody can contribute, it differs from a paper-based reference source in important ways. In particular, older articles tend to be more comprehensive and balanced, while newer articles more frequently contain significant misinformation, unencyclopedic content, or vandalism. Users need to be aware of this to obtain valid information and avoid misinformation that has been recently added and not yet removed (see Researching with Wikipedia for more details). However, unlike a paper reference source, Wikipedia is continually updated, with the creation or updating of articles on topical events within seconds, minutes, or hours, rather than months or years for printed encyclopedias.

What Wikipedia is not will give an understanding of how to consult or contribute to Wikipedia. Further information on key topics appears below. Further advice is at Frequently asked questions, advice for parents, or see Where to ask questions. For help with editing and other issues, see Help:Contents.