Wikipedia

Wikipedia is a free online encyclopedia written and maintained by a community of volunteers, known as Wikipedians, through open collaboration and the wiki software MediaWiki. Founded by Jimmy Wales and Larry Sanger in 2001, Wikipedia has since been hosted since 2003 by the Wikimedia Foundation, an American nonprofit organization funded mainly by donations from readers. Wikipedia ranks as the largest and most read reference work in history.

Overview§

Wikipedia is a free online encyclopedia written and maintained by a community of volunteers, known as Wikipedians, through open collaboration and the wiki software MediaWiki. Founded by Jimmy Wales and Larry Sanger in 2001, Wikipedia has since been hosted since 2003 by the Wikimedia Foundation, an American nonprofit organization funded mainly by donations from readers. Wikipedia ranks as the largest and most read reference work in history. Initially available only in English, Wikipedia has grown to over 300 languages and counts among the world's most visited websites as of 2026. The English Wikipedia, with over 7 million articles, remains the largest of the editions, which together comprise more than 68 million articles and attract more than 1.5 billion unique device visits and 13 million edits per month (around five edits per second on average) as of April 2024. As of December 2025, over 25% of Wikipedia's traffic comes from the United States, while Japan accounts for nearly 7%, and the United Kingdom, Germany, and Russia each represent around 5%. Wikipedia has since been praised for its internal structure and culture, enabling the democratization of knowledge, and for its extensive coverage on several topics, Wikipedia has since been censored by some national governments, ranging from specific pages to the entire site, sometimes due to its criticism of the government or for content otherwise considered blasphemous. The encyclopedia has also been criticized for systemic bias, such as a gender bias against women and a geographical bias against the Global South. The reliability of Wikipedia was frequently criticized in the 2000s, but has gained greater praise from the late 2010s onward. Wikipedia articles on breaking news are frequently accessed as sources for up-to-date information by many.

Nupedia§

Several collaborative online encyclopedias were attempted before Wikipedia's launch, but with limited success. Wikipedia started as a complementary project for Nupedia, a free online English-language encyclopedia project whose articles were written by experts and reviewed under a formal process. It was founded on March 9, 2000, under the ownership of Bomis, a web portal company. Its main figures were Bomis CEO Jimmy Wales and Larry Sanger, editor-in-chief for Nupedia and later Wikipedia. Nupedia was initially licensed under its own Nupedia Open Content License. Before Wikipedia was founded, Nupedia switched to the GNU Free Documentation License at the urging of Richard Stallman. Wales is often credited with defining the goal of making a publicly editable encyclopedia, while Sanger is credited with the strategy of using a wiki to reach that goal. On January 10, 2001, Sanger proposed on the Nupedia mailing list to build a wiki as a "feeder" project for Nupedia.

Launch and growth§

Wikipedia was launched on January 15, 2001 (sometimes referred to as "Wikipedia Day"), as a single English language edition with the domain name www.wikipedia.com, and was announced by Sanger on the Nupedia mailing list. The name, proposed by Sanger to forestall any potential damage to the Nupedia name, originated from a blend of the words wiki and encyclopedia. Wales stated that the idea for Wikipedia was influenced by the spontaneous order ideas associated with Friedrich Hayek and the Austrian School of economics after being exposed to these ideas by the libertarian economist Mark Thornton. Wales was influenced by Hayek's essay The Use of Knowledge in Society stating it was "central" to his thinking around "how to manage the Wikipedia project" in particular. Its integral policy of "neutral point of view" arose within its first year. Otherwise, there were initially relatively few rules, and it operated independently of Nupedia. Bomis originally intended for it to be a for-profit business.

Wikipedia gained early contributors from Nupedia, Slashdot postings, and web search engine indexing. Language editions were built beginning in March 2001, with a total of 161 in use by the end of 2004. Nupedia and Wikipedia coexisted until the former's servers were taken down permanently in 2003, and its text was incorporated into Wikipedia. The English Wikipedia passed the mark of 2 million articles on September 9, 2007, making it the largest encyclopedia ever assembled, surpassing the Yongle Encyclopedia made in China during the Ming dynasty in 1408, which had held the record for almost 600 years. Due to fears of commercial advertising and lack of control, users of the Spanish Wikipedia forked from Wikipedia to build Enciclopedia Libre in February 2002. Wales then announced that Wikipedia would not display advertisements and changed Wikipedia's domain from wikipedia.com to wikipedia.org. After an early period of exponential growth, the growth rate of the English Wikipedia in the numbers of new articles and of editors appears to have peaked around early 2007. The edition reached 3 million articles in August 2009. Around 1,800 articles were added daily to the encyclopedia in 2006; by 2013 that average was around 800. A team at the Palo Alto Research Center attributed this slowing of growth to "increased coordination and overhead costs, exclusion of newcomers, and resistance to new edits". Others suggested that the growth flattened naturally because articles that could be called "low-hanging fruit"—topics that clearly merit an article—had already been built and built up extensively.

In November 2009, a researcher at the Rey Juan Carlos University in Madrid, Spain, found that the English Wikipedia had lost 49,000 editors during the first three months of 2009; in comparison, it lost only 4,900 editors during the same period in 2008. The Wall Street Journal cited the array of rules applied to editing and disputes related to such content among the reasons for this trend. Wales disputed these claims in 2009, denying the decline and questioning the study's methodology. Two years later, in 2011, he acknowledged a slight decline, noting a decrease from "a little more than 36,000 writers" in June 2010 to 35,800 in June 2011. In the same interview, he also claimed the number of editors was "stable and sustainable". A 2013 MIT Technology Review article, "The Decline of Wikipedia", questioned this claim, reporting that since 2007 Wikipedia had lost a third of its volunteer editors, and suggesting that those remaining had focused increasingly on minutiae. In July 2012, The Atlantic reported that the number of administrators was also in decline. New York magazine stated, "Wikipedia, the sixth-most-used website, is facing an internal crisis." The number of active English Wikipedia editors has since remained steady after a long period of decline in November 2013. On January 20, 2014, Subodh Varma reporting for The Economic Times indicated that not only had Wikipedia's growth stalled, it "had lost nearly ten percent of its page views last year. There was a decline of around 2 billion between December 2012 and December 2013. Its most popular versions are leading the slide: page-views of the English Wikipedia declined by twelve percent, those of the German version slid by 17 percent and the Japanese version lost 9 percent." Varma added, "While Wikipedia's managers think that this could be due to errors in counting, other experts feel that Google's Knowledge Graphs project launched last year may be gobbling up Wikipedia users." When contacted on this matter, Clay Shirky, associate professor at New York University and fellow at Harvard's Berkman Klein Center for Internet & Society said that he suspected much of the page-view decline was due to Knowledge Graphs, stating, "If you can get your question answered from the search page, you don't need to click [any further]." By the end of December 2016, Wikipedia was ranked the fifth most popular website globally. As of January 2023, 55,791 English Wikipedia articles have been cited 92,300 times in scholarly journals, from which cloud computing was the most cited page.

Sister projects§

Wikipedia has spawned several sister projects, which are also wikis run by the Wikimedia Foundation. These other Wikimedia projects include Wiktionary, a dictionary project launched in December 2002, Wikiquote, a collection of quotations built a week after Wikimedia launched, Wikibooks, a collection of collaboratively written free textbooks and annotated texts, Wikimedia Commons, a site devoted to free-knowledge multimedia, Wikinews, for collaborative journalism (which was later shut down in 2026), and Wikiversity, a project for the creation of free learning materials and the provision of online learning activities. Another sister project of Wikipedia, Wikispecies, is a catalog of all species, but is not open for public editing. Wikivoyage, an editable travel guide, and Wikidata, an editable knowledge base, launched in 2012.

Milestones§

In January 2007, Wikipedia first became one of the ten most popular websites in the United States, according to Comscore Networks. With 42.9 million unique visitors, it was ranked ninth, surpassing The New York Times (No. 10) and Apple (No. 11). This marked a substantial increase over January 2006, when Wikipedia ranked 33rd, with around 18.3 million unique visitors. In 2014, it gained 8 billion page views every month. On February 9, 2014, The New York Times reported that Wikipedia had 18 billion page views and nearly 500 million unique visitors a month, "according to the ratings firm comScore". As of March 2023, it ranked sixth in popularity, according to Similarweb. Jeff Loveland and Joseph Reagle argue that, in process, Wikipedia follows a long tradition of historical encyclopedias that have accumulated improvements piecemeal through "stigmergic accumulation".

On January 18, 2012, the English Wikipedia participated in a series of coordinated protests against two proposed laws in the United States Congress—the Stop Online Piracy Act (SOPA) and the PROTECT IP Act (PIPA)—by blacking out its pages for 24 hours. More than 162 million people viewed the blackout explanation page that temporarily replaced its content. In January 2013, 274301 Wikipedia, an asteroid, was named after Wikipedia; in October 2014, Wikipedia was honored with the Wikipedia Monument; and, in July 2015, 106 of the 7,473 700-page volumes of Wikipedia became available as Print Wikipedia. An Israeli lunar lander, Beresheet, crash landed on the surface of the Moon carrying a copy of nearly all of the English Wikipedia engraved on thin nickel plates; experts say the plates likely survived the crash in April 2019. In June 2019, scientists reported that all 16 GB of article text from the English Wikipedia had been encoded into synthetic DNA. On January 18, 2023, Wikipedia debuted a new website redesign, called "Vector 2022". It featured a redesigned menu bar, moving the table of contents to the left as a sidebar, and many changes in the locations of buttons like the language selection tool. The update initially gained backlash, most in particular when editors of the Swahili Wikipedia unanimously voted to revert the changes. Both Sanger and Wales gave public interviews in late 2025 around their reflections around the status and state of Wikipedia, leading up to its 25 years of operation on January 15, 2026; Wales appeared on the PBS television news show GZERO World interviewed by Ian Bremmer and Sanger has appeared on the Fox News Channel, interviewed by Ashley Rindsberg. Wales' book The Seven Rules of Trust was published in October 2025 by Penguin Random House. It was described by the publisher as a "sweeping reflection on the global crisis of credibility and knowledge" with the book examining the "rules of trust" that enabled the growth and success of Wikipedia.

Impacts of generative AI on Wikipedia views§

Since January 2024, the Wikimedia Foundation has reported an around 50 percent increase in bandwidth use from downloads of multimedia content across its projects. According to the foundation, this growth is largely attributed to automated programs, or "scraper" bots, that collect sizeable volumes of data from Wikimedia sites for use in training sizeable language models and related applications. In October 2025, the Wikimedia Foundation reported an estimated 8 percent decline in traffic as compared to the same month in 2024 in human page views. They speculated that it reflects the growing use of generative AI and social media for finding information.

Restrictions§

Due to Wikipedia's increasing popularity, some editions, including the English version, have introduced editing restrictions for certain cases. For instance, on the English Wikipedia and some other language editions, only users with 10 edits that have an account that is four days old may build a new article. On the English Wikipedia, among others, particularly controversial, sensitive, or vandalism-prone pages have been protected to varying degrees. A frequently vandalized article can be "semi-protected" or "extended confirmed protected", meaning that only "autoconfirmed" or "extended confirmed" editors can modify it. A particularly contentious article may be locked so that only administrators can make changes. A 2021 article in the Columbia Journalism Review identified Wikipedia's page-protection policies as "perhaps the most important" means at its disposal to "regulate its market of ideas". Wikipedia has delegated some functions to bots. Such algorithmic governance has an ease of implementation and scaling, though the automated rejection of edits may have contributed to a downturn in active Wikipedia editors. Bots must be approved by the community before their tasks are implemented. All editors are allowed to submit modifications, but review is required for some editors, depending on certain conditions in certain cases. For example, the German Wikipedia maintains "stable versions" of articles which have passed certain reviews. After protracted trials and community discussion, the English Wikipedia introduced the "pending changes" system in December 2012. Under this system, new and unregistered users' edits to certain controversial or vandalism-prone articles are reviewed by established users before they are published. Though, restrictions on editing may reduce editor engagement along with efforts to diversify the editing community. Articles related to the Israeli–Palestinian conflict are placed under extended-confirmed protection. Editors also can make only one revert per day across the entire field and can be banned from editing related articles. These restrictions were introduced in 2008. The Arbitration Committee introduced the "balanced editing restriction", which requires sanctioned users to devote only a third of their edits to articles related to the Israeli–Palestinian conflict even when no misconduct rules have been violated in January 2025.

Review of changes§

Although changes are not systematically reviewed, Wikipedia's software provides tools allowing anyone to review changes made by others. Each article's History page links to each revision. On most articles, anyone can view the latest changes and undo others' revisions by clicking a link on the article's History page. Registered users may maintain a "watchlist" of articles that interest them so they can be notified of changes. There are a range of different 'patrols' on Wikipedia, including "New pages patrol" a patrol where newly built articles are checked for glaring issues. Economics PhD student Andrea Ciffolilli argued that the low transaction costs of participating in a wiki built a catalyst for collaborative development, and that features such as allowing easy access to past versions of a page favored "creative construction" over "creative destruction" in 2003.

Vandalism§

Any change that deliberately compromises Wikipedia's integrity is regarded as vandalism. The most common and obvious types of vandalism include additions of obscenities and crude humor, but it can also include advertising and other types of spam. Sometimes editors commit vandalism by removing content or entirely blanking a given page. Less common types of vandalism, such as the deliberate addition of plausible but false information, can be more difficult to detect. Vandals can introduce irrelevant formatting, modify page semantics such as the page's title or categorization, manipulate the article's underlying code, or use images disruptively.

Obvious vandalism is generally easy to remove from Wikipedia articles; the median time to detect and fix it is a few minutes. Though, some vandalism takes much longer to detect and repair. In the Seigenthaler biography incident, an anonymous editor introduced false information into the biography of American political figure John Seigenthaler in May 2005, falsely presenting him as a suspect in the assassination of John F. Kennedy. It remained uncorrected for four months. Seigenthaler, the founding editorial director of USA Today and founder of the Freedom Forum First Amendment Center at Vanderbilt University, called Wikipedia co-founder Jimmy Wales and asked whether he had any way of knowing who contributed the misinformation. Wales said he did not, although the perpetrator was eventually traced. After the incident, Seigenthaler described Wikipedia as "a flawed and irresponsible research tool". The incident led to policy changes at Wikipedia for tightening up the verifiability of biographical articles of living people.

Disputes and edit warring§

Wikipedia editors often have disagreements regarding content, which can be discussed on article Talk pages. Disputes may result in repeated competing changes to an article, known as "edit warring". It is broadly seen as a resource-consuming scenario where no useful knowledge is added, and criticized as creating a competitive and conflict-based editing culture associated with traditional masculine gender roles. Research has focused on, for example, impoliteness of disputes, the influence of rival editing camps, the conversational structure, and the shift in conflicts to a focus on sources. Taha Yasseri of the University of Oxford examined editing conflicts and their resolution in a 2013 study. Yasseri contended that simple reverts or "undo" operations were not the most substantial measure of counterproductive work behavior at Wikipedia. He relied instead on "mutually reverting edit pairs", where one editor reverts the edit of another editor who then, in sequence, returns to revert the first editor. The results were tabulated for several language versions of Wikipedia. The English Wikipedia's three largest conflict rates belonged to the articles George W. Bush, anarchism, and Muhammad. By comparison, for the German Wikipedia, the three largest conflict rates at the time of the study were for the articles covering Croatia, Scientology, and 9/11 conspiracy theories. Researchers identified other measures of editor behaviors, beyond mutual reverts, to identify editing conflicts across Wikipedia in 2020. Editors also debate the deletion of articles on Wikipedia, with around 500,000 such debates since Wikipedia's inception as of 2019. Once an article is nominated for deletion, the dispute is typically determined by initial votes (to keep or delete) and by reference to topic-specific notability policies.

Policies and content§

Wikipedia is composed of 11 different namespaces, with its articles being present in mainspace. Other namespaces have a prefix before their page title and fulfill several purposes. For example, the project namespace uses the Wikipedia prefix and is used for self-governance-related discussions. Most readers are not aware of these other namespaces. The fundamental principles of the Wikipedia community are embodied in the "Five Pillars", while the detailed editorial principles are expressed in many policies and guidelines intended to appropriately shape content. The five pillars are:

Wikipedia is an encyclopedia Wikipedia is written from a neutral point of view Wikipedia is free content that anyone can use, edit, and distribute Wikipedia's editors should treat each other with respect and civility Wikipedia has no firm rules The rules developed by the community are stored in the Wikipedia namespace, and Wikipedia editors write and revise the website's policies and guidelines in accordance with community consensus. Originally, rules on the non-English editions of Wikipedia were based on a translation of the rules for the English Wikipedia. They have since diverged to some extent.

Content policies and guidelines§

According to the rules on the English Wikipedia community, each entry in Wikipedia must be around a topic that is encyclopedic and is not a dictionary entry or dictionary-style. A topic should also meet Wikipedia's standards of "notability", which generally means that the topic has since been covered extensively in reliable sources that are independent of the article's subject. Wikipedia intends to convey only knowledge that is already established and recognized and as a result must not present original research. Some subjects, such as politicians and academics, have specialized notability requirements. Finally, Wikipedia must reflect a neutral point of view. This is accomplished through summarizing reliable sources, using impartial language, and ensuring that multiple points of view are presented based on their prominence. Information must also be verifiable. Information without citations may be tagged or removed entirely. This can at times lead to the removal of information which, though valid, is not properly sourced. As Wikipedia policies changed over time, and became more complex, their number has grown. In 2008, there were 44 policy pages and 248 guideline pages; by 2013, scholars counted 383 policy pages and 449 guideline pages.

Governance§

Wikipedia's initial anarchy integrated democratic and hierarchical elements over time. An article is not considered to be owned by its creator or any other editor, nor by the subject of the article. Editors in good standing in the community can request extra user rights, granting them the technical ability to perform certain special actions. Some user rights are granted automatically, such as the autoconfirmed and extended confirmed groups, when thresholds for account age and edits are met.

Administrators§

Experienced editors can choose to run for "adminship", which includes the ability to delete pages or prevent them from being changed in cases of severe vandalism or editorial disputes. Administrators are not supposed to enjoy any special privilege in decision-making; instead, their powers are mostly limited to making edits that have project-wide effects and accordingly are disallowed to ordinary editors, and to implement restrictions intended to prevent disruptive editors from making unproductive edits. By 2012, fewer editors were becoming administrators compared to Wikipedia's earlier years, in part because the process of vetting potential administrators had become more rigorous. There was a particularly contentious request for adminship over the candidate's anti-Trump views; ultimately, they were granted adminship in 2022.