
In the U.S., video games usually carry ratings from the Entertainment Software Ratings Board (ESRB) to indicate the type of content contained in the game. These ratings include E (Everyone), T (Teen), M (Mature) and AO (Adult Only) and others. They are also accompanied by notes of the material in the game like violence, drug use and strong language. The Entertainment Software Association (ESA) disagrees with limiting games due to their ratings or content and says the restriction violates consumers first amendment rights.
Source:
Macworld