Group that was VOLUNTARILY founded by game publishers to reduce the political heat generated by violent games. Does NOT mandate the sales of M rated games to minors, retailers do. The ESRB's flaw is that the panel's of reviewers who watch footage of games are almost entirely non-gamers. Also, the rating levels are a bit hipocritical if you know how to walk the line.
(Lots of violence can be had in a T rated game, but blood almost certainately guarantees a M rating. Much like the MPAA's hipocracy of rating a film R after the second "fuck" or when used to mean sex.)
Dissafected 13 year old suburban freak: I wish to buy this M rated game and I WANT IS RIGHT NOOOOW!
Clerk: Are you 17, that is the store policy?
Punk ass: FUCK THE ESRB THIS IS THEIR FAULT!!!