NC-17 originally stood for 'No Children Under 17 Admitted' to combat the misconception that the rating indicated a film was pornographic. The NC-17 rating replaced the X rating in 1990 as the X rating was not trademarked by the MPA and had been co-opted by the pornography industry.
The rating may be issued because of violence, sex, drugs, or other elements.
The rating does not designate films as pornographic or obscene, but simply that the content is suitable only for adults. It is assigned to films the MPA believes most parents would consider 'patently adult' and not suitable for their children under 18. NC-17 ( No One 17 and Under Admitted) is the highest rating in the Motion Picture Association (MPA) film rating system used for films distributed in the United States.