A restricted rating is one that restricts its audience to a particular group of people, usually to prevent underage children from seeing large amounts of violence, strong language, or sexual content. In the MPAA rating system, the two restricted ratings are R and NC-17. R is a part-restricted rating, that is, people under 17 can see an R-rated picture in a cinema, if they're accompanied by a parent or adult guardian. NC-17 is a fully restricted rating, and nobody under 18 may see a picture with this rating, especially if accompanied by an adult. Adult ratings may be restricted to make sure that underage children aren't exposed to pornography or excessive violence, as well as coarse or sexually explicit language and drug (mis)use.