Movie rating system indicates which movies are safe to watch for children and teenagers. G rating is safe for all audiences. PG rating indicates some parenta guidance may be requires for certain topics raised in the movie. PG-13 rating shows that some material may be inappropriate for kids under 13.
R movie rating stands for Restricted and there will be some Adult material that parents need to be mindful of. Finally, NC-17 is the strictest film rating with no kids admitted.