Launch and early growth
Review of changes
Main article: Vandalism on Wikipedia
Any change or edit that manipulates content in a way that purposefully compromises the integrity of Wikipedia is considered vandalism. The most common and obvious types of vandalism include additions of obscenities and crude humor. Vandalism 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 to an article can be more difficult to detect. Vandals can introduce irrelevant formatting, modify page semantics such as the page's title or categorization, manipulate the underlying code of an article, or use images disruptively. American journalist John Seigenthaler (1927–2014), subject of the Seigenthaler incident. Obvious vandalism is generally easy to remove from Wikipedia articles; the median time to detect and fix vandalism is a few minutes. However, some vandalism takes much longer to repair.
In the Seigenthaler biography incident, an anonymous editor introduced false information into the biography of American political figure John Seigenthaler in May 2005. Seigenthaler was falsely presented as a suspect in the assassination of John F. Kennedy. The article 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 replied that he did not, although the perpetrator was eventually traced. After the incident, Seigenthaler described Wikipedia as "a flawed and irresponsible research tool". This incident led to policy changes at Wikipedia, specifically targeted at tightening up the verifiability of biographical articles of living people.
In 2010, Daniel Tosh encouraged viewers of his show, Tosh.0, to visit the show's Wikipedia article and edit it at will. On a later episode, he commented on the edits to the article, most of them offensive, which had been made by the audience and had prompted the article to be locked from editing.