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Wikipedia is an online free-content encyclopediaproject helping to create a world in which everyone can freely share in the sum of all knowledge. It is supported by the Wikimedia Foundation and based on a model of freely editable content. The name "Wikipedia" is a blending of the words wiki (a technology for creating collaborative websites, from the Hawaiian 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 Internet access can write and make changes to Wikipedia articles, except in limited cases where editing is restricted to prevent further disruption or vandalism.

Since its creation on January 15, 2001, Wikipedia has grown into the world's largest reference website, attracting 1.7 billion unique visitors monthly as of November 2020. It currently has more than fifty-six million articles in more than 300 languages, including 6,318,589 articles in English with 132,916 active contributors in the past month.

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.

Anyone is allowed to add or edit words, references, images, and other media here. What is contributed is more important than who contributes it. To remain, the content must be free of copyright restrictions and contentious material about living people. It must fit within Wikipedia's policies, including being verifiable against a published reliable source. Editors' opinions and beliefs and unreviewed research will not remain. Contributions cannot damage Wikipedia because the software allows easy reversal of mistakes, and many experienced editors are watching to ensure that edits are improvements. Begin by simply clicking the Edit button at the top of any editable page!

Wikipedia is a live collaboration differing from paper-based reference sources in important ways. It is continually created and updated, with articles on new events appearing within minutes, rather than months or years. Because everybody can help improve it, Wikipedia has become more comprehensive than any other encyclopedia. Besides quantity, its contributors work on improving quality, removing or repairing misinformation, and other errors. Over time, articles tend to become more comprehensive and balanced. However, because anyone can click "edit" at any time and add content, any article may contain undetected misinformation, errors, or vandalism. Readers who are aware of this can obtain valid information, avoid recently added misinformation (see Wikipedia:Researching with Wikipedia), and fix the article.

Wikipedia was founded as an offshoot of Nupedia, a now-abandoned project to produce a free encyclopedia, begun by the online media company Bomis. Nupedia had an elaborate system of peer review and required highly qualified contributors, but articles' writing was slow. During 2000, Jimmy Wales (founder of Nupedia and co-founder of Bomis), and Larry Sanger, whom Wales had employed to work on the encyclopedia project, discussed ways of supplementing Nupedia with a more open, complementary project. Multiple sources suggested that a wiki might allow public members to contribute material, and Nupedia's first wiki went online on January 10, 2001.

There was considerable resistance on the part of Nupedia's editors and reviewers to the idea of associating Nupedia with a website in the Wiki format, so the new project was given the name "Wikipedia" and launched on its own domain, wikipedia.com, on January 15 (now called "Wikipedia Day" by some users). The bandwidth and server (in San Diego) were donated by Wales. Other current and past Bomis employees who have worked on the project include Tim Shell, one of the cofounders of Bomis and its current CEO, and programmer Jason Richey.

In May 2001, a large number of non-English Wikipedias were launched—in Catalan, Chinese, Dutch, Esperanto, French, German, Hebrew, Italian, Japanese, Portuguese, Russian, Spanish, and Swedish. These were soon joined by Arabic and Hungarian. In September,[2] Polish was added, and further commitment to the multilingual provision of Wikipedia was made. At the end of the year, Afrikaans, Norwegian, and Serbo-Croatian versions were announced.

The domain was eventually changed to the present wikipedia.org when the Wikimedia Foundation was launched, in 2003, as its new parent organization with the ".org" top-level domain denoting its not-for-profit nature. Today, there are Wikipedias in more than 300 languages.

Anyone with Web access can edit Wikipedia, and this openness encourages the inclusion of a tremendous amount of content. About 130,000 editors—from expert scholars to casual readers—regularly edit Wikipedia, and these experienced editors often help to create a consistent style throughout the encyclopedia, following our Manual of Style.

Several mechanisms are in place to help Wikipedia members carry out the important work of crafting a high-quality resource while maintaining civility. Editors can watch pages, and technically skilled persons can write editing programs to track or rectify bad edits. Where there are disagreements on how to display facts, editors often work together to compile an article that fairly represents current expert opinion on the subject. Aspiring authors may wish to read the information on Contributing to Wikipedia before contributing to the project.

Although the Wikimedia Foundation owns the site, it is largely uninvolved in writing and daily operations.

"Wikipedia" is a registered trademark of the not-for-profit Wikimedia Foundation, which has created a family of free-content projects that are built by user contributions.

Most of Wikipedia's text and many of its images are dual-licensed under the Creative Commons Attribution-Sharealike 3.0 Unported License (CC-BY-SA) and the GNU Free Documentation License (GFDL) (unversioned, with no invariant sections, front-cover texts, or back-cover texts). Some text has been imported only under CC-BY-SA and CC-BY-SA-compatible license and cannot be reused under GFDL; such text is identified either on the page footer, in the page history, or on the discussion page of the article that utilizes the text. Every image has a description page that indicates the license under which it is released or, if it is non-free, the rationale under which it is used.

Contributions remain their creators' property, while the CC-BY-SA and GFDL licenses ensure the content is freely distributable and reproducible. (See content disclaimer for more information.)

Text on Wikipedia is a collaborative work, and the efforts of individual contributors to a page are recorded in that page's history, which is publicly viewable. Information on the authorship of images and other media, such as sound files, can be found by clicking on the image itself or the nearby information icon to display the file page, which includes the author and source, where appropriate, along with other information.

Many visitors come to Wikipedia to acquire knowledge, while others come to share knowledge. At this very instant, dozens of articles are being improved, and new articles are also being created. Changes can be viewed at the Recent changes page and a random page at random articles. 5,929 articles have been designated by the Wikipedia community as featured articles, exemplifying the best articles in the encyclopedia. Another 34,192 articles are designated as good articles. Some information on Wikipedia is organized into lists; the best of these are designated as featured lists. Wikipedia also has portals, which organize content around topic areas. Articles can be found using the search box on the screen's top-right side or, if using the Monobook skin, a bit lower along the left-hand side.

Wikipedia is available in languages other than English. Wikipedia has more than 300 languages, including a Simple English version, and related projects include a dictionary, quotations, books, manuals, and scientific reference sources, and a news service (see sister projects). All these are maintained, updated, and managed by separate communities and often include information and articles that can be hard to find through other common sources.

Wikipedia articles are all cross-referenced. Highlighted text like this means "click here" for in-depth information. (Hovering is probably deep enough.) There are other links towards the ends of most articles, for other articles of interest, relevant external websites and pages, reference material, navigational templates, and organized categories of knowledge which can be searched and traversed in a loose hierarchy for more information. Some articles may also have links to dictionary definitions, audio-book readings, quotations, the same article in other languages, and further information on our sister projects. Additional links can be easily made if a relevant link is missing—this is one simple way to contribute.

What's a love dart? Wikipedia can help you find out! (2:13 min)

As wiki documents, articles are never considered complete and may be continually edited and improved. Over time, this generally results in an upward trend of quality and a growing consensus over a neutral representation of information.

Users should be aware that not all articles are of encyclopedic quality from the start: they may contain false or debatable information. Indeed, many articles start their lives as displaying a single viewpoint; and, after a long process of discussion, debate, and argumentation, they gradually take on a neutral point of view reached through consensus. For a while, others may become caught up in a heavily unbalanced viewpoint that can take some time—months or years perhaps—to achieve better-balanced coverage of their subject. In part, this is because editors often contribute content in which they have a particular interest and do not attempt to make each article they edit comprehensive. However, additional editors eventually expand and contribute to articles and strive to achieve balance and comprehensive coverage. Also, Wikipedia operates several internal resolution processes that can assist when editors disagree on content and approach. Usually, editors eventually reach a consensus on ways to improve the article.

The ideal Wikipedia article is well written, balanced, neutral, and encyclopedic, containing comprehensive, notable, verifiable knowledge. An increasing number of articles reach this standard over time, and many already have. Our best articles are called Featured Articles (and display a small star in the upper right corner of the article), and our second-best tier of articles are designated Good Articles. However, this process can take months or years to be achieved through editors' concerted effort. Some articles contain statements that have not yet been fully cited. Others will later be augmented with new sections. Some information will be considered by later contributors to be insufficiently founded and, therefore, may be removed.

While the overall trend is toward improvement, it is important to use Wikipedia carefully if it is intended to be used as a research source. Individual articles will vary in quality and maturity by their nature. Guidelines and information pages are available to help users and researchers do this effectively, as is an article that summarizes third-party studies and assessments of the reliability of Wikipedia.

Like a paper encyclopedia, Wikipedia attempts to compile world knowledge but is not bound by the restrictions of a paper encyclopedia. Illustration from Nuremberg Chronicle 1493

Wikipedia has advantages over traditional paper encyclopedias. First, it is not limited in space: it can keep growing as fast as people add.

Second, there are no qualifications required to be able to author its articles. It draws from a vast pool of contributors: the whole world. This, and the first advantage mentioned above, have enabled Wikipedia to become the most comprehensive encyclopedia on Earth.

Third, a paper encyclopedia remains static (stays the same) and falls out of date until its next edition. Wikipedia is more dynamic: You don't have to wait for the next edition to come out (there are no editions), as Wikipedia is published online as it is written online. Articles are made available as is, regardless of what stage of development they are in. You can update Wikipedia at any moment. People do so continually around the clock, thereby helping each other keep abreast of the most recent events everywhere and the latest facts in every subject.

Fourth, Wikipedia has a meager "publishing" cost for adding or expanding entries, as it is online, with no need to buy paper or ink for distribution. This has allowed it to be made available for free, making it more accessible to everyone. This has also enabled Wikipedia to be independently developed and published in many different languages simultaneously by people literate in each. Of the 290+ different language Wikipedias, 137 of them have 10,000 or more articles.

Fifth, Wikipedia has a low environmental impact in some respects, since it never needs to be printed. However, computers have their own environmental cost.

Sixth, Wikipedia is extra-linear (more than linear). Instead of in-line explanations, Wikipedia incorporates hypertext in the form of wikilinks. Throughout its content is a robust network of links, providing another dimension of knowledge accessibility. The encyclopedia also has correlated to tables of contents and indexes, with each entry in them hyperlinked to an article on the topic specified.

Seventh, each Wikipedia article provides an introduction summarizing the more extensive detail of its contents.

Eighth, being open to anyone to edit, articles on Wikipedia are subject to additions that might be erroneous or written poorly, which in turn are subject to being corrected or rewritten. It is a community effort, with most people involved helping to improve the work, fixing problems they encounter along the way. See more about Wikipedia's strengths and weaknesses below ...

The Wikipedia Monument (2014) by Mihran Hakobyan in Slubice, Poland, honors the Wikipedia community.

Wikipedia's greatest strengths, weaknesses, and differences arise because it is open to anyone. According to editorial guidelines and policies, it has a large contributor base, and its articles are written by consensus.

The MediaWiki software that runs Wikipedia retains a history of all edits and changes. Thus information added to Wikipedia never "vanishes" irreversibly. Discussion pages are an important resource on contentious topics. Therefore, serious researchers can often find a wide range of vigorously or thoughtfully advocated viewpoints not present in the consensus article. As with any source, the information should be checked. A 2005 editorial by a BBC technology writer comments that these debates are probably symptomatic of cultural changes that are happening across all sources of information (including search engines and the media) and may lead to "a better sense of how to evaluate information sources." [3]

Wikipedia disclaimers apply to all pages on Wikipedia. However, the consensus in Wikipedia is to put all disclaimers only as links and at the end of each article. Proposals to have a warning box at the beginning have been rejected. Some do not like the way it looks or that it calls attention to possible errors in Wikipedia.

Wikipedia, in common with many websites, has a disclaimer that, at times, has led to commentators citing these to support the view that Wikipedia is unreliable. A selection of similar disclaimers from places which are often regarded as reliable (including sources such as Encyclopædia Britannica, Associated Press, and the Oxford English Dictionary) can be read and compared at Wikipedia:Non-Wikipedia disclaimers.

A downloadable "Editing Wikipedia guide" in PDF form written by the staff at the Wikimedia Foundation

Go ahead and be bold—click the edit button! (1:06 min)

Anyone can contribute to Wikipedia by clicking on the Edit tab in an article, and editors are encouraged to be bold. To get started, the intro tutorial has helpful advice. Also, creating an account offers many benefits. Editors are expected to add only verifiable and factual information rather than personal views and opinions, and to remain civil when discussing issues. Vandals will have their edits reverted and be blocked from editing.

Most articles start as stubs, but after many contributions, they can become featured articles. All editors are unpaid volunteers, including administrators, trusted editors who are given elevated permissions. The ease of editing Wikipedia results in many people editing. That makes updating the encyclopedia very quick. Every page has an associated talk page tab, where improvements to it are discussed.

Video guided tour #2: Why does Wikipedia work even though anyone can edit it?

As well as systems to catch and control substandard and vandalistic edits, Wikipedia also has a full style and content manual and various positive systems for continual article review and improvement. Examples of the processes include peer review, good article assessment, and the featured article process, a rigorous review of articles that are intended to meet the highest standards and showcase Wikipedia's capability to produce high-quality work.

Besides, specific types of articles or fields often have their own specialized and comprehensive projects, assessment processes (such as biographical article assessment), and expert reviewers within specific subjects. Nominated articles are also frequently the subject of specific focus on the neutral point of view noticeboard or in WikiProject Cleanup.

Wikipedia uses MediaWiki software, the open-source program used not only on Wikimedia projects but also on many other third-party websites. The hardware supporting the Wikimedia projects is based on several hundred servers in various hosting centers worldwide. Full descriptions of these servers and their roles are available on this Meta-Wiki page. For technical information about Wikipedia, check Technical FAQ. Wikipedia publishes various types of metadata; and, across its pages, are many thousands of microformats.

Wikipedia is run as a communal effort. It is a community project whose result is an encyclopedia. Feedback about the content should, in the first instance, be raised on the discussion pages of those articles. Be bold and edit the pages to add information or correct mistakes.

The Help:Contents may be accessed by clicking help displayed under the ► Interaction tab at the top left of all pages.

There is an established escalation-and-dispute process within Wikipedia and pages designed for questions, feedback, suggestions, and comments. For a full listing of the services and assistance that can be requested on Wikipedia, see Wikipedia:Request directory.

See also:

Facilities to help users researching specific topics can be found at:

Because of Wikipedia's nature, it is encouraged that people looking for information should try to find it themselves in the first instance. If, however, information is found to be missing from Wikipedia, please be bold and add it.

For a listing of ongoing discussions and current requests, see the dashboard. For specific discussion not related to article content or editor conduct, see the Village pump, which covers such subjects as milestone announcements, policy and technical discussion, and information on other specialized portals such as the help, reference and peer review desks. The Community portal is a centralized place to find things to do, collaborations, and general editing to help information and find out what is happening. The Signpost, a community-edited newspaper, has recent news regarding Wikipedia, its sister projects, and the Wikimedia Foundation.

To contact individual contributors, leave a message on their talk page. Standard places to ask policy and project-related questions are the Village pump, online, and the Wikipedia mailing lists, over e-mail. Reach other Wikipedians via IRC and e-mail.

Besides, the Wikimedia Foundation Meta-Wiki is a site for coordinating the various Wikipedia projects and sister projects (and abstract discussions of policy and direction). Also available are places for submitting bug reports and feature requests.

For a full list of contact options, see Wikipedia:Questions.

This Wikipedia is written in English. Many other Wikipedias are available; some of the largest are listed below.

1,000,000+ articles

العربية‎ Deutsch Español FrançaisItaliano Nederlands 日本語Polski Português РусскийSvenska Українська Tiếng Việt中文

250,000+ articles

Bahasa Indonesia Bahasa MelayuBân-lâm-gú Български CatalàČeština Dansk EsperantoEuskara فارسی‎ עברית‎ 한국어Magyar Norsk Bokmål RomânăSrpski Srpskohrvatski SuomiTürkçe

50,000+ articles

Asturianu Bosanski EestiΕλληνικά Simple English GalegoHrvatski Latviešu Lietuviųമലയാളം МакедонскиNorsk nynorsk Slovenčina​Slovenščina ไทย

Wikipedia is hosted by the Wikimedia Foundation, a non-profit organization that also hosts a range of other projects:

Content is available under CC BY-SA 3.0 unless otherwise noted.