4chan was first set up in 2003 but has since become an online cultural phenomenon - home to creative jokers but also malicious hackers

The leak of hundreds of private photographs stolen from celebrities has caused a stir online, with the images first posted to 4chan on Sunday evening before being circulated online via Reddit and Twitter.

But just what is 4chan and why was it the hacker’s first port of call to post the stolen photographs?

First created in 2003, 4chan is a controversial message board that's reviled as much as it is celebrated. The site is sub-divided into a number of sections or ‘boards’ where anonymous users can discuss everything from video games and travel to pornography and hacking.

Unlike other online forums, users don’t create consistent identities and posts aren’t recorded. On the more popular boards comments can disappear within minutes as they’re pushed ‘off the bottom of the page’ by newer posts.

These two factors have created 4chan’s chaotic, anarchic and surprisingly creative atmosphere. As an anonymous collective, its users are responsible for some of the best known internet memes online (including rickrolling and lolcats) but its lack of regulation means it’s also home to a great deal of questionable and straight-forwardly criminal content.

Video: 4chan hacker releases nude photos of celebrities

The site’s most popular board is /b/, designated for ‘random’ discussions, and is frequently filled with NSFW or ‘Not Safe for Work’ content. This can vary from soft-core pornography to gore and shock images, and it was here that an anonymous hacker posted the stolen celebrity pictures over the weekend.