Wikipedia is a multilingual, web-based, free-contentencyclopedia project supported by the Wikimedia Foundation and based on a model of openly editable content. The name "Wikipedia" is a portmanteau of the words wiki (a technology for creating collaborative websites, from theHawaiian word wiki, meaning "quick") and encyclopedia. Wikipedia's articles provide links designed to guide the user to related pages with additional information.Wikipedia is written collaboratively by largely anonymous volunteers who write without pay. Anyone with Internetaccess can write and make changes to Wikipedia articles, except in limited cases where editing is restricted to prevent disruption or vandalism. Users can contribute anonymously, under a pseudonym, or, if they choose to, with their real identity.The fundamental principles by which Wikipedia operates are the five pillars. The Wikipedia community has developed many policies and guidelines to improve the encyclopedia; however, it is not a formal requirement to be familiar with them before contributing.Since its creation in 2001, Wikipedia has grown rapidly into one of the largest reference websites, attracting 374 million unique visitors monthly as of September 2015.[1] There are about 70,000 active contributors working on more than 41,000,000 articles in 29languages. As of today, there are 5,310,922 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 thestatistics page for more information.)People of all ages, cultures and backgrounds can add or edit article prose, references, images and other media here. What is contributed is more important than the expertise or qualifications of the contributor. What will remain depends upon whether the content is free of copyright restrictions and contentious materialabout living people, and whether it fits within Wikipedia's policies, including being verifiable against a published reliable source, thereby excluding editors'opinions and beliefs and unreviewed research. Contributions cannot damage Wikipedia because the software allows easy reversal of mistakes and many experienced editors are watching to help ensure that edits are cumulative improvements. Begin by simply clicking the Edit link at the top of any editable page!

Wikipedia is a live collaboration differing from paper-based reference sources in important ways. Unlike printed encyclopedias, Wikipedia is continually created and updated, with articles on historic events appearing within minutes, rather than months or years. Because everybody can help improve it, Wikipedia has become more comprehensive than any other encyclopedia. In addition to quantity, its contributors work on improving quality as well. Wikipedia is a work-in-progress, with articles in various stages of completion. As articles develop, they tend to become more comprehensive and balanced. Quality also improves over time as misinformation and other errors are removed or repaired. However, because anyone can click "edit" at any time and add stuff in, any article may contain undetected misinformation, errors, or vandalism. Awareness of this helps the reader to obtain valid information, avoid recently added misinformation (seeWikipedia:Researching with Wikipedia), and fix the article.