In the mid-2000s, the imageboard was becoming a central hub for internet subcultures, memes, and anonymous discussion. Because of its "no-registration" policy and lack of formal archives, it also became a target for people looking to share illegal and harmful content, specifically Child Sexual Abuse Material (CSAM) .

The thread is immediately deleted by a mod for being "too high quality."

: In several high-profile cases, such as the investigation into the "Operation Lost Boy" or the "Playpen" site (though distinct from 4chan), data gathered from monitoring these public boards led investigators to the private servers and IP addresses of the distributors.

Lurking on /b/ at 3 AM because sleep is for the weak and the employed.

4chan relies on a small team of volunteer moderators ("janitors") and automated filters. Because threads move so quickly (especially on /b/ ), illegal images can sometimes remain visible for minutes or hours before being deleted.