What Is 4chan, the Site at Heart of Celebrity Photo Scandal?

— -- The scandal over hacked nude photos of Jennifer Lawrence, Kate Upton and other celebrities has renewed focus on a maverick website that has been linked to pornography, activists hackers like Anonymous, violent memes that include Slender Man, as well as online pranks.

The nude photos in this latest incident, which appear to show several A-listers in various states of undress, were posted on the popular image-sharing site 4chan and spread rapidly through social media.

Hackers Post Alleged Naked Pics of Jennifer Lawrence, Kate Upton, Other Celebs

After Nude Photo Hack, Should Cloud Users Be Worried?

Although it's not confirmed how the images made it online or how they were obtained, an anonymous 4chan user boasted he had gathered the cache of nude photos of dozens of celebrities by hacking into their personal accounts and then posted them on the site.

Reps for Lawrence and Upton have confirmed photos posted of them on 4chan are real, but other celebs whom the alleged leaker claimed to have targeted say the photos posted showing them are fakes.

The operators of 4chan did not immediately respond to an ABC News' request for comment.

So What Is 4chan?

4chan.com is an online image-focused bulletin board website where users can anonymously share photos, GIFs and videos, as well as comment on each others' posts. To launch a discussion, a user has to post an image. Then others can comment or reply with more images.

Discussions are broken up into main topic boards, ranging from Japanese anime and video games to travel and literature to the paranormal. The "/b/" board, dubbed the "random" imageboard, is 4chan's largest and historically most controversial board.

Who Uses 4chan?

4chan has over 20 million unique visitors per month and has more than 1.6 billion posts, according to the site.

Unlike other social media or content sharing sites, 4chan users don't have to create an account to participate in discussions, and users can respond to posts as "Anonymous."

How Long Has 4chan Been Around?

Christopher Poole, who posts under the username "moot," founded 4chan in 2003, modeling it after a Japanese imageboard website. He started sharing it on The Something Awful Forums, another online bulletin board.

What Is 4chan Used For?

Over the years, 4chan has grown into a massive user-generated content sharing forum, spawning Internet campaigns and becoming an online community for Internet subcultures.

But 4chan has also been surrounded by controversy. While some content is harmless, several posts include vulgar language, obscene jokes, pornography, violence and gore.

Discussions about Slender Man, the fictional horror character popularized by internet memes that have led to violent attacks, have been linked to 4chan and other message board sites. The infamous activist hacker group Anonymous "first emerged on imageboards like 4chan," according to author Parmy Olson's book, "We Are Anonymous."

This latest celebrity photo scandal is not the first time a 4chan user has boasted about an apparent hacking. In 2008, a user posted an alleged detailed account of how he hacked into then-Alaska Gov. Sarah Palin's private Yahoo! email account during the 2008 presidential campaign.

4chan users have also been linked to numerous online pranks. Last year, one of 4chan's users started a group effort to create a fake Apple ad that claimed a new update in the iOS 7 operating system would make iPhones waterproof. Within a few hours, a sleek fake ad using Apple's font style, colors and graphics was created and spread through social media.