It used to be that movies weren't rated. All movies released in the US has to meet the Motion Picture Production Code (the "Hays Code") that was put into place in 1930. This lasted until 1968!
Jack Valenti became the president of the Motion Picture Association of American (MPAA) in 1966. He thought the Hays Code reeked of censorship and didn't serve modern movies. So the MPAA came up with its ratings system. It started out as:
G: General Audiences
M: Suggested for mature audiences - Parental discretion advised
R: Restricted – Persons under 16 not admitted, unless accompanied by parent or adult guardian. (That was later raised to 17)
X: Persons under 16 not admitted (that was later raised to 18).
The MPAA didn't copyright the "X" rating and the porn industry took it over. And what's better than one X but three, so "XXX" became synonymous with porn. And putting out an X-rated film was box office death.
I watched another movie (Hellfighters) recently that was made in 1968. It was rated "G" but had enough violence these days it would have been rated "PG" at least. But that was early in the rating system and likely they didn't want to rate it "M."
In 1970, "M" was change to GP (General Audiences/parental guidance suggested).
In 1972, GP was change to PG (Parental Guidance suggested)
This system lasted until 1984. Then came Indiana Jones and the Temple of Doom. It was rated PG. But the violence was, to many audiences, shocking. So the MPAA came up with PG-13 (Parents strongly cautioned – Some material may be inappropriate for children under 13).
And in 1990, X was replaced with the completely unsexy NC-17 (No children under 17, which was later changed to no children 17 and under). NC-17 is still box office death. But at least it isn't synonymous with porn.
(The only NC-17 film I've seen is Ang Lee's Lust, Caution)
When I was a kid (in the 70s), kids' movies were all rated G. Adult films were either PG or R.
But now, I've noticed, kids' movies are all PG, adult movies are PG-13 or R. And you can have one (and only one) instance of the F-word in a PG-13 film. Two, and you have an R-rating. And R-rated films do not make as much money as PG-13 films. About the only movies that are G rated are nature documentaries.
I don't make movie decisions based on rating. I enjoy all sorts of movies but I have noticed a large majority of movies are PG-13.
Do you used movie ratings as a guide to what to watch, or what to let the kids watch? Let me know in the comments below.