July 1st marked the 25th birthday of the PG-13 rating. This sparked due to the big gap inbetween the PG and R ratings. Movies such as Gremlins and Poltergeist were both rated PG and it was suggest by Spielberg to fill this gap between PG and R. Just think of the ratings these days with comedies such as Pineapple Express, Tropic Thunder and Knocked Up paving the way for more adult R comedies. Videoeta has written an article on the evolution of the PG-13 rating and you can read it here.