Wikipedia (pronounced as Template:IPA or Template:IPA, also Template:IPA) is a multilingual Web-based free-content encyclopedia. Wikipedia is written collaboratively by volunteers, allowing articles to be changed by anyone with access to a web browser. The project began on January 15 2001 as a complement to the expert-written Nupedia, and is now operated by the non-profit Wikimedia Foundation. Wikipedia has more than 2,550,000 articles, including more than 893,000 in the English-language version. Since its inception, Wikipedia has steadily risen in popularity, and its success has spawned several sister projects. There has, however, been much controversy over its reliability.
Wikipedia is regularly cited by both the mass media and academia, sometimes critically, and sometimes to praise it for its free distribution, editing, and diverse coverage. Editors are encouraged to uphold a policy of "neutral point of view" under which notable perspectives are summarized without an attempt to determine an objective truth. But Wikipedia's status as a reference work has been controversial. Its open nature allows vandalism, inaccuracy, inconsistency, uneven quality, and unsubstantiated opinions. It has also been criticised for systemic bias, preference of consensus to credentials, and a perceived lack of accountability and authority when compared with traditional encyclopedias.
There are over 200 language editions of Wikipedia, around 100 of which are active. Twelve editions have more than 50,000 articles each: English, German, French, Japanese, Polish, Italian, Swedish, Dutch, Portuguese, Spanish, Chinese and Russian. Its German-language edition has been distributed on DVD-ROM, and many of its other editions are mirrored or have been forked by websites.
Wikipedia's slogan is "The Free Encyclopedia that anyone can edit", and the project is described by its founder Jimmy Wales as "an effort to create and distribute a free encyclopedia of the highest possible quality to every single person on the planet in their own language." It is developed on the wikipedia.org website using a type of software called a "wiki", a term originally used for the WikiWikiWeb and derived from the Hawaiian Wiki Wiki, which means "quick". Wales intends that Wikipedia should achieve a "Britannica or better" quality and be published in print.
Several other encyclopedia projects exist or have existed on the Internet. Traditional editorial policies and article ownership are used in some, such as the expert-written Stanford Encyclopedia of Philosophy and the now-defunct Nupedia. More casual websites such as h2g2 or Everything2 serve as general guides, the articles of which are written and controlled by individuals. Projects such as Wikipedia, Susning.nu, and the Enciclopedia Libre are wikis in which articles are developed by numerous authors, and there is no formal process of review. Wikipedia has become the largest such encyclopedic wiki by article and word-count. Unlike many encyclopedias, it has licensed its content under the GNU Free Documentation License.
Wikipedia has a set of policies identifying types of information appropriate for inclusion. These policies are often cited in disputes over whether particular content should be added, revised, transferred to a sister project, or removed.
The GNU Free Documentation License (GFDL), the license through which Wikipedia's articles are made available, is one of many "copyleft" copyright licenses that permit the redistribution, creation of derivative works, and commercial use of content provided its authors are attributed and this content remains available under the GFDL. When an author contributes original material to the project, the copyright over it is retained with them, but they agree to make the work available under the GFDL. Material on Wikipedia may thus be distributed to, or incorporated from, resources which also use this license. Wikipedia's content has been mirrored or forked by hundreds of resources from database dumps. Although all text is available under the GFDL, a significant percentage of Wikipedia's images and sounds are non-free. Items such as corporate logos, song samples, or copyrighted news photos are used with a claim of fair use. Material has also been given to Wikipedia under no-derivative or for-Wikipedia-only conditions. However, some editions only accept free media.
News organizations have referred to Wikipedia articles as sources or in sidebars containing related information on the Web, some regularly. According to lists maintained by Wikipedia's editors, its articles have been cited most frequently in the news media. Less frequently, it has been used in academic studies, books, conferences, and court cases. For instance, the Parliament of Canada website refers to Wikipedia's article on same-sex marriage in the "further reading" list of Bill C-38. Noncomprehensive lists of such uses are maintained by Wikipedians. 
Wikipedia encompasses 119 "active" language editions as of March 2005. Its five largest editions are, in descending order, English, German, French, Japanese, and Polish. In total, Wikipedia contains 205 language editions of varying states with a combined 2.6 million articles.
Language editions operate independently of one another. Editions are not bound to the content of other language editions, and are only held to global policies such as "neutral point of view". Articles and images are nonetheless shared between Wikipedia editions, the former through pages to request translations organized on many of the larger language editions, and the latter through the Wikimedia Commons repository. Translated articles represent only a small portion of articles in any edition.
The following is a list of the larger editions, sorted by number of articles as of 18 December 2005. (The article count, however, is a very limited metric for comparing the editions. For instance, in some Wikipedia versions nearly half of the articles are stubs which were created automatically by robots.) 
- English (1,083)
- German (329,457)
- French (207,851)
- Japanese (165,149)
- Polish (148,963)
- Italian (126,929)
- Swedish (122,207)
- Dutch (113,810)
- Portuguese (88,409)
- Spanish (80,213)
- Chinese (50,168)
- Russian (49,338)
- Norwegian Bokmål (44,576)
- Finnish (41,602)
- Danish (35,931)
Almost all visitors may edit Wikipedia's articles, and registered users can create new ones and have their changes instantly displayed. Wikipedia is built on the expectation that collaboration among users will improve articles over time, in much the same way that open-source software develops. Further, this real-time, collaborative model allows rapid updating of existing topics and introduction of new topics. The authors need not have any expertise or formal qualifications in the subjects which they edit, and users are warned that their contributions may be "edited mercilessly and redistributed at will" by anyone who so wishes. Its articles are not controlled by any particular user or editorial group. Decision-making on the content and editorial policies of Wikipedia is instead done by consensus and occasionally by vote. Jimmy Wales retains final judgement on Wikipedia policies and user guidelines.
By the nature of its openness, "edit wars" and prolonged disputes often occur when editors do not agree. A few members of its community have explained its editing process as a collaborative work, a "socially Darwinian evolutionary process", but this is not generally considered by the community to be an accurate self-description. Articles are always subject to editing, unless the article is protected for a short time due to vandalism or revert wars; therefore, Wikipedia does not declare any article finished. Some users attempt to enter malicious or amusing but irrelevant information, but changes of this sort are normally removed quickly.
Regular users often maintain a 'watchlist' of articles of interest to them, so that they are immediately shown which of these articles have changed since their last log in. This allows monitoring of daily editing to prevent false information and spam, and also to keep up with other editors' views, or updates, of the subjects on the watchlist.
Because of the Wiki-principle, all edits of a Wikipedia article are kept in an edit history which can be looked at by everyone. Therefore, Wikipedia is also the first major encyclopedia ever where everybody can see how an article evolved over time and if, how and where the content of an article was controversial. All controversial standpoints which were once voiced and afterwards deleted and even plain page vandalism remain visible for everyone and provide additional information about the article's topic and its degree of controversy and add the dimension of time to every article.
Wikipedia content is being distributed in several ways. In addition to the main Web site at wikipedia.org, its content is mirrored on many other web servers.
Aside from distribution in online form, printed and print-ready versions of Wikipedia are gaining in popularity. So called WikiReaders have been started by German Wikipedia in late February 2004 with Thomas Karcher's WikiReader about Sweden being the first. German WikiReaders about Sweden, Nauru, and Internet are available in print form from http://www.wikireader.de and several others as print-ready PDF files with printed versions in preparation for sale. Following this example, WikiReader projects have been initiated from Chinese, English, French, and Polish Wikipedians.
CD and DVD versions of Wikipedia are also available. The German Wikipedia project was the first with a shipped release in 2004, being currently in its second edition (ISBN 3-89853-020-5). The English Wikipedia is expected to follow at the end of 2005.
Mobile phone Wikipedia is available for almost all Java enabled Mobile phones in English and German. The Reader Software is Freeware provided by InteracT!V and can be downloaded for free. The JOCA application is also a full mobile phone RSS Reader and EPG. You can search online the Wikipedia database. The system converts the results for optimal presentation on mobile phones. All data is transferred packed to optimize the usability and to reduce the data traffic costs.
Wikipedia is currently available for handhelds in English, German, Spanish, French, Polish, Italian and Esperanto. The reader software TomeRaider required to access the Wikipedia data files is shareware (around $20 as of Nov. 2005). The data files themselves can be downloaded free of charge from the Wikipedia download area, purchased on CD, or compiled using conversion scripts. Instructions can be found on the page of the script author Erik Zachte. On most handhelds the huge size of the Wikipedia data files requires an extension card.
- Main article: History of Wikipedia
Wikipedia began as a complementary project of Nupedia, a free online encyclopedia project whose articles were written by experts through a formal process. Nupedia was founded on 9 March 2000 under the ownership of Bomis, Inc, a Web portal company. Its principal figures were Jimmy Wales, Bomis CEO, and Larry Sanger, editor-in-chief for Nupedia and later Wikipedia. Nupedia was described by Sanger as differing from existing encyclopedias in being open content; not having size limitations, as it was on the Internet; and being free of bias, due to its public nature and potentially broad base of contributors. Nupedia had a seven-step review process by appointed subject-area experts, but was later widely viewed as too slow for producing a limited number of articles. Funded by Bomis, there were initial plans to recoup its investment by the use of advertisements. It was licensed under its own Nupedia Open Content License initially, switching to the GNU Free Documentation License prior to Wikipedia's founding at the urging of Richard Stallman.
On January 10, 2001, Larry Sanger proposed on the Nupedia mailing list to create a wiki alongside Nupedia. Under the subject "Let's make a wiki", he wrote:
No, this is not an indecent proposal. It's an idea to add a little feature to Nupedia. Jimmy Wales thinks that many people might find the idea objectionable, but I think not. (...) As to Nupedia's use of a wiki, this is the ULTIMATE "open" and simple format for developing content. We have occasionally bandied about ideas for simpler, more open projects to either replace or supplement Nupedia. It seems to me wikis can be implemented practically instantly, need very little maintenance, and in general are very low-risk. They're also a potentially great source for content. So there's little downside, as far as I can see.
Wikipedia was formally launched on 15 January 2001, as a single English-language edition at wikipedia.com, and announced by Sanger on the Nupedia mailing list. It had been, from 10 January, a feature of Nupedia.com in which the public could write articles that could be incorporated into Nupedia after review. It was relaunched off-site after Nupedia's Advisory Board of subject experts disapproved of its production model. Wikipedia thereafter operated as a standalone project without control from Nupedia. Its policy of "neutral point-of-view" was codified in its initial months, though it is similar to Nupedia's earlier "nonbias" policy. There were otherwise few rules initially. Wikipedia gained early contributors from Nupedia, Slashdot postings, and search engine indexing. It grew to approximately 20,000 articles among 18 language editions by the end of its first year. It had 26 language editions by the end of 2002, 46 by the end of 2003, and 161 by the end of 2004. Nupedia and Wikipedia coexisted until the former's servers went down, permanently, in 2003, and its text was incorporated into Wikipedia.
Wales and Sanger attribute the concept of using a wiki to Ward Cunningham's WikiWikiWeb or Portland Pattern Repository. Wales mentioned that he heard the concept first from Jeremy Rosenfeld, an employee of Bomis who showed him the same wiki, in December 2000, but it was after Sanger heard of its existence from Ben Kovitz, a regular at this wiki, in January 2001, and proposed a creation of a wiki for Nupedia to Wales that Wikipedia's history started. Under a similar concept of free content, though not wiki production, the GNUPedia project existed alongside Nupedia early in its history. It subsequently became inactive and its creator, free-software figure Richard Stallman, lent his support to Wikipedia.
Citing fear of commercial advertising and lack of control in a perceived English-centric Wikipedia, users of the Spanish Wikipedia forked from Wikipedia to create the Enciclopedia Libre in February 2002. Later that year, Wales announced that Wikipedia would not display advertisements, and moved its website to wikipedia.org. Projects have since forked from Wikipedia's content for editorial reasons, such as Wikinfo, which abandoned "neutral point-of-view" in favor of multiple complementary articles written from a "sympathetic point-of-view."
From Wikipedia and Nupedia, the Wikimedia Foundation was created on June 20, 2003. Wikipedia and its sister projects thereafter operated under this non-profit organization. Wikipedia's first sister project, "In Memoriam: September 11 Wiki" had been created in October 2002 to detail the September 11, 2001 attacks; Wiktionary, a dictionary project, was launched in December 2002; Wikiquote, a collection of quotes, a week after Wikimedia launched; and Wikibooks, a collection of collaboratively-written free books, the next month. Wikimedia has since started a number of other projects, detailed below.
Wikipedia has traditionally measured its status by article count. In its first two years, it grew at a few hundred or fewer new articles per day. The English Wikipedia reached a 100,000 article milestone on January 22, 2003. In 2004, its article growth rate was approximately 1,000 to 3,000 per day in all editions. In the English edition it reached 500,000 articles on February 25, 2004. Wikipedia reached its one millionth article among 105 language editions on September 20, 2004.
The brand Wikipedia has been trademarked in the European Union (January 20th 2005), Japan (December 16th, 2004) and the USA (September 14th, 2004) in the area "Provision of information in the field of general encyclopedic knowledge via the Internet" by the Wikimedia Foundation. There are currently plans to license the usage of the Wikipedia trademark for some products like books or DVDs.
Details are described on meta:Wikimedia trademarks.
Software and hardware
Wikipedia is run by MediaWiki free software on a cluster of dedicated servers located in Florida and three other locations around the world. MediaWiki is Phase III of the program's software. Originally, Wikipedia ran on UseModWiki by Clifford Adams (Phase I). At first it required CamelCase for links; later it was also possible to use double brackets. Wikipedia began running on a PHP wiki engine with a MySQL database in January 2002. This software, Phase II, was written specifically for the Wikipedia project by Magnus Manske. Several rounds of modifications were made to improve performance in response to increased demand. Ultimately, the software was rewritten again, this time by Lee Daniel Crocker. Instituted in July 2002, this Phase III software was called MediaWiki. It was licensed under the GNU General Public License and used by all Wikimedia projects.
Wikipedia was served from a single server until 2003, when the server setup was expanded into an n-tier distributed architecture. In January 2005, the project ran on 39 dedicated servers located in Florida. This configuration included a single master database server running MySQL, multiple slave database servers, 21 web servers running the Apache software, and seven Squid cache servers. By September 2005, its server cluster had grown to around 100 servers in four locations around the world.
Page requests are processed by first passing to a front-end layer of Squid caching servers. Requests that cannot be served from the Squid cache are sent to two load-balancing servers running the Perlbal software, which then pass the request to one of the Apache web servers for page-rendering from the database. The web servers serve pages as requested, performing page rendering for all the Wikipedias. To increase speed further, rendered pages for anonymous users are cached in a filesystem until invalidated, allowing page rendering to be skipped entirely for most common page accesses. Wikimedia has begun building a global network of caching servers with the addition of three such servers in France. A new Dutch cluster is also online now. In spite of all this, Wikipedia page load times remain quite variable. The ongoing status of Wikipedia's website is posted by users at a status page on OpenFacts.
- Wikibooks, for free textbooks;
- Wikinews, for free news;
- Wikiquote, a free anthology of quotations;
- Wikisource, a free library;
- Wikispecies, a free directory of life;
- and Wiktionary, a free dictionary.
In addition, two special projects serve all of the sister projects (including Wikipedia) in all of their languages at once. These are:
- the Wikimedia Commons, which is a shared media repository (images, sound, video) that can be utilized by all Wikimedia wikis;
- and the Wikimedia Meta-Wiki for coordination and planning across all projects.
Here is a list of alternate spellings for Wikipedia according to the language editions:
- Bichipedia - Sardinian
- Biquipedia - Aragonese
- Uichipedia - Aromanian
- Uiquipedia - Asturian
- Vicipéid - Irish
- Vikipedio - Esperanto
- Vikipedi - Turkish
- Vikipeedia - Estonian
- Viquipèdia - Catalan
- Vicipaedia - Latin
- Wicipedia - Welsh
- Wikipédia - French, Portuguese, Hungarian
- Wikipedia - English, Breton, Danish, Dutch, Finnish, Somali, German, Italian, Nauruan, Norwegian, Polish, Romanian, Sicilian, Spanish, Swedish, Tagalog
- Wikipedio - Ido
- ويكيبيديا - Arabic
- วิกิพีเดีย - Thai
- ウィキペディア - Japanese
- Wéijībǎikē 维基百科 - Chinese
- Βικιπαίδεια - Greek
- Уикипедия - Bulgarian
- ויקיפדיה - Hebrew
- ויקיפעדיע - Yiddish
- Википедия - Русский (Russian)
- Вікіпедія - Українська (Ukrainian)
- Wikipedija - Bosanski, , Hrvatski, Srpskohrvatski/Српскохрватски, Slovenian
- ویکیپدیا - Farsi
- Википедиja - Македонски, Srpskohrvatski/Српскохрватски, Cpпcки
- ვიკიპედია - Georgian
- विकिपीडिया - Hindi
- ویـکـیـپـیـڈ یـا - Urdu
- uikiPEdi,as - Lojban
- 위키백과 - 한국어 (Korean)
- ವಿಕಿಪೀಡಿಯ - ಕನ್ನಡ (Kannada)
- Internet encyclopedia project
- Uncyclopedia, parody of Wikipedia
- Criticism of Wikipedia
- Who writes Wikipedia
- ^ See plots at "Visits per day", Wikipedia Statistics, 1 January 2005.
- ^ Jimmy Wales, "Wikipedia is an encyclopedia", 8 March 2005, <email@example.com>.
- ^ For example, see statistics and licenses on the English edition at "Wikipedia:Image copyright tags", Wikipedia (9 March 2005).
- ^ Andrew Lih, "Wikipedia as Participatory Journalism: Reliable Sources? Metrics for evaluating collaborative media as a news resource" (PDF), 5th International Symposium on Online Journalism, April 2004.
- ^ "Wikipedia:Wikipedia as a press source 2005", Wikipedia (28 March 2005).
- ^ "C-38", LEGISINFO (28 March 2005).
- ^ Wikipedia:Wikipedia as a source
- ^ "Complete list of language Wikipedias available", Meta-Wiki (22 May 2005).
- ^ "All languages", Wikipedia statistics, 21 March 2005.
- ^ For example, "Wikipedia: Translation into English," Wikipedia. (9 March 2005).
- ^ "Complete list of language Wikipedias available", Meta Wikimedia (28 March 2005).
- ^ "Power structure", Meta-Wiki, 10:55 4 April 2005.
- ^ "Wikipedia:Edit war", Wikipedia (26 March 2005).
- ^ "Wikipedia sociology", Meta-Wiki, 23:30 24 March 2005.
- ^ Template:Citenewsauthor
- ^ Template:Web reference
- ^ Larry Sanger, "Q & A about Nupedia", Nupedia, March 2000.
- ^ Larry Sanger, "Q & A about Nupedia", Nupedia, March 2000.
- ^ Template:News reference
- ^ Template:News reference
- ^ Template:Citenewsauthor
- ^ "Wikipedia:Multilingual statistics", Wikipedia, 30 March 2005.
- ^ Jimmy Wales, "Re: Sanger's memoirs", 20 April 2005,<firstname.lastname@example.org>.
- ^ Template:Citenewsauthor
- ^ Template:Citenewsauthor
- ^ Jimmy Wales: "Announcing Wikimedia Foundation", 20 June 2003, <email@example.com>.
- ^ "500,000 Wikipedia articles", Wikimedia Foundation, 25 February 2004.
- ^ See "Wikipedia Reaches One Million Articles", Wikimedia Foundation, 20 September 2004.
- ^ Template:News reference
- Fernanda B. Viegas, Martin Wattenberg, and Kushal Dave, "Studying Cooperation and Conflict between Authors with history flow Visualizations", CHI 2004 April 24 - April 29 2004. Preliminary report "History Flow" available on the IBM website.
- Wikipedia:Wikipedia in academic studies
- Wikipedia:Press releases
- Wikipedia:Press coverage
- Wikipedia:Why Wikipedia is not so great
- Wikipedia:Replies to common objections
- Open Directory Project: Wikipedia
- OpenFacts: Copies of Wikipedia content
- SourceWatch: Wikipedia
- wikipedia.org, multi-lingual portal
- en.wikipedia.org, English language edition
- Meta-Wiki, policy-related and technical discussions regarding Wikimedia
- Wikimedia Foundation, parent organization of Wikipedia
- Larry Sanger on the origins of Wikipedia from MemoryWiki.org
- BBC article showing flaws in wikipedia
- Guardian UK article
- "Interview with Wikipedia founder Jimmy Wales," nPost, November 1 2005.
- Good example of making use of Wiki on a Pink Floyd website
- Wikipedia ASCII Art Collection, with rss-feed and XML serialization
- Wikipedia Signpost, newspaper about the English Wikipedia
- Wikipedia in the news. Aggregated news and rss-feed.(Multilingual)
- Why Wikipedia will survive the storm, from News.com
- How Stuff Works-Wikipedia, A brief guide about how Wikipedia works
- Nature comparison between Wikipedia and Britannica
- Criticism of the Wikipedia, An opinion of the downside of Wikipedia.
- Wikipedia Founder Edits Own Bio, Wired article on Jimbo vs Sanger
- A false Wikipedia 'biography', the USA Today editorial which sparked the late 2005 controversy.
- Wikipedia Class Action, a planned lawsuit against Wikimedia.
- Wikipedia Watch, an unfavorable website
- Nature: Wikipedia as accurate as Britannica, Nature article finds that Wikipedia is about as accurate as encyclopedia Britannica when it comes to science entires.
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