G - "General Audiences." Appropriate for all ages. Often geared toward kids. No nudity, no drugs, no sex, minimal violence, and limited use of language that goes beyond polite conversation.
PG - "Parental Guidance Suggested" May have mild violence and/or action, mild language and sexual references, BRIEF nudity (revealing attire), intense images, sexual themes, crude humor or very mild drug references.
PG-13 - May contain moderate language, minimal strong language, some explicit nudity, intense violence, gore, or mild drug content. This is the highest unrestricted rating.
R - "Restricted." May contain very strong language or strong sexual emphasis, strong explicit nudity, strong violence and gore, or strong drug content.
NC-17 - "No Children under 17." May contain very strong sexual or offensive language, strong explicit nudity, very strong gore or disturbing violence, or graphic drug abuse. Films with this rating are usually edited to get a "R" rating.