Launched by Christopher "moot" Poole in October 2003, the site hosts boards dedicated to a wide variety of topics, from video games and television to literature, cooking, weapons, music, history, technology, anime, physical fitness, politics, and sports, among others.

4chan has often been the subject of media attention as a source of controversies, including the coordination of pranks and harassment against websites and Internet users, and the posting of illegal and offensive content as a result of its lax censorship and moderation policies.

Most boards have their own set of rules and are dedicated to a specific topic, including anime and manga, video games, music, literature, fitness, politics, and sports, among others.

[22] Gianluca Stringhini, an associate professor at Boston University College of Engineering, said in August 2024, "The only moderation on the platform appears to be for clearly illegal content, such as child pornography.

[25] Poole had been a regular participant on Something Awful's subforum "Anime Death Tentacle Rape Whorehouse" (ADTRW), where many users were familiar with the Japanese imageboard format and Futaba Channel ("2chan.net").

Additionally, a lolicon board was created at /l/ (Lolikon),[31] but was disabled following the posting of genuine child pornography and ultimately deleted in October 2004, after threats of legal action.

[37] By this point, 4chan's culture had altered, moving away from the "early, more childish," humour, as evident by the likes of Project Chanology; trolling underwent a so-called "golden age" that took aim at American corporate media.

In January 2011, Poole announced the deletion of the /r9k/ ("ROBOT9000") and /new/ (News) boards, saying that /new/ had become devoted to racist discussions, and /r9k/ no longer served its original purpose of being a test implementation of xkcd's ROBOT9000 script.

The submitted documents also revealed RapeApe lamenting that 4chan was "getting the shaft" over the Buffalo terrorist attack and his attempt to persuade the advertising platform Bid.Glass to reverse their exit from the website.

[65][66] In April 2010, Poole testified in the trial United States of America v. David Kernell as a government witness,[67] explaining the terminology used on 4chan to the prosecutor, ranging from "OP" to "lurker", as well as the nature of the data given to the FBI as part of the search warrant, including how users can be uniquely identified from site audit logs.

[11] Christopher Poole told The New York Times, in a discussion on the moderation of /b/, that "the power lies in the community to dictate its own standards" and that site staff simply provided a framework.

[72][74] A significant amount of media coverage is in response to /b/'s culture, which has been characterized as adolescent, crude[72][11] and spiteful,[6] with one publication writing that their "bad behavior is encouraged by the site's total anonymity and the absence of an archive".

[6] Mattathias Schwartz of The New York Times likened /b/ to "a high-school bathroom stall, or an obscene telephone party line",[72] while Baltimore City Paper wrote that "in the high school of the Internet, /b/ is the kid with a collection of butterfly knives and a locker full of porn.

[89] Publications such as Pitchfork and Entertainment Weekly noted the board played a significant role in popularizing various music artists, such as Death Grips,[90][91] Neutral Milk Hotel,[92] Car Seat Headrest,[93] and Have a Nice Life.

[102] An alleged unreleased Radiohead song, titled "Putting Ketchup in the Fridge" and "How Do You Sit Still", was initially reported as genuine by NME and Spin until CNN revealed it was a hoax promoted by the board's users.

[108] A role-playing game based on Neutral Milk Hotel's In the Aeroplane Over the Sea, designed with help from the board's users, received coverage from Polygon[109] and Pitchfork.

A stickied thread on its front page states that the board's intended purpose is "discussion of news, world events, political issues, and other related topics.

[40][112] Although there had previously been a strong left-libertarian contingent to 4chan activists, there was a gradual rightward turn on 4chan's politics board in the early-mid 2010s, with the fundamentalist approach to free speech contributing.

The board has spawned multiple Internet memes, most notably the NPC Wojak in 2016 (derived from the gaming term non-player character to describe those who do not think for themselves or make their own conscious decisions).

[154] A lolcat is an image combining a photograph of a cat with solecistic text intended to contribute humour, widely popularized by 4chan in the form of a weekly post dedicated to them and a corresponding theme.

[39] A link to the YouTube video of Tay Zonday's song "Chocolate Rain" was posted on /b/ on July 11, 2007, and then subsequently circulated by users, becoming a very popular internet meme.

[179] KTTV Fox 11 aired a report on Anonymous, calling them a group of "hackers on steroids", "domestic terrorists", and collectively an "Internet hate machine" on July 26, 2007.

[181] On July 10, 2008, the swastika CJK unicode character (卐) appeared at the top of Google's Hot Trends list—a tally of the most used search terms in the United States—for several hours.

[185] The stock price of Apple Inc. fell significantly in October 2008 after a hoax story was submitted to CNN's user-generated news site iReport.com claiming that company CEO Steve Jobs had suffered a major heart attack.

After coming back up, the front page accidentally revealed a backup file of the entire website, which contained over 300 megabytes of private company emails, which were leaked to several torrents and across several sites on the Internet.

[198][199] On October 18, 2006, the Department of Homeland Security warned National Football League officials in Miami, New York City, Atlanta, Seattle, Houston, Oakland, and Cleveland about a possible threat involving the simultaneous use of dirty bombs at stadiums.

Promptly after the blast, I, along with two ther Anonymous, will charge the building, armed with a Bushmaster AR-15, IMI Galil AR, a vintage, government-issue M1 .30 Carbine, and a Benelli M4 semi auto shotgun.

"[220] The indictment alleged that he posted anonymously to /pol/ the day after the Unite the Right rally, communicating an intention to attack protestors at an upcoming right-wing demonstration, ostensibly to elicit sympathy for the alt-right movement.

[239] On July 26, 2009, AT&T's DSL branch temporarily blocked access to the img.4chan.org domain (host of /b/ and /r9k/), which was initially believed to be an attempt at Internet censorship, and met with hostility on 4chan's part.

[242] 4chan's founder Christopher Poole responded with the following:[243][244] In the end, this wasn't a sinister act of censorship, but rather a bit of a mistake and a poorly executed, disproportionate response on AT&T's part.