.xxx is a proposed top-level domain (TLD) intended as a voluntary option for sexually explicit sites on the Internet. The name is inspired by the former MPAA and BBFC "X" rating, now commonly applied to pornographic movies as "XXX". ICANN announced in June 1, 2005 that .xxx would become a sponsored top-level domain similar to .aero, .travel, etc. but it was never implemented. On May 10, 2006, ICANN reversed its decision, and on March 30, 2007, ICANN rejected the .xxx proposal a third time

As of 2005, there is an alternative implementation of .xxx by New.net, a private domain registration service unaffiliated with ICANN, via an alternative DNS root. Its future - including that of domain names previously registered with New.net - is uncertain in the wake of the ICANN-sanctioned TLD announcement.

Another unofficial .xxx TLD was previously available through the alternative DNS root system administered by the now-defunct AlterNIC.