Through their innovative ratings system, the MPAA sees itself as the appointed guardians of all generations of man and the single-standing force that prevents thematic violence and swearing from flooding the USA. No-one else thinks that though.
It was a pretty shitty time to be a film-maker in the 1900's; aside from the threat of ********, ************, and *********************, any films you produced had to be passed through over 40 censorship boards throughout the US, all of which could basically tell you to recut your film over and over again lest you be blacklisted from that area. Some of these were local censorship boards, some were city censorship boards, and some were state censorship boards. Distinctions between them don't really matter though, because no matter who was sitting behind that desk (we presume they all used desks), they all had equal billing in the stage production that was 'kicking your ass'.
There was a concession break halfway through, though; they weren't that sadistic
People, for some reason, grew pretty tired of this system, and in 1930, the MPAA (then known as the Motion Picture Producers and Distributors of America or MPPDA) started ruining the shit out of these censor bureaus with the recently-released Hays Code. At last! A fair system whereby film-makers only had to stick to one set of guidelines; pass this, they promised, and be given free rein over the fertile lands that were the American cinematic landscape. Which, under this new code, it wouldn't if it contained any allusions to homosexuality. Or featured black people. Or portrayed sex between two unmarried people as being awesome. Or showed criminals going unpunished. In short, anything remotely fun or thought-provoking was dropped in favour of some of the whitest, straightest films this side of Leni Riefenstahl.
Further proving that nothing can ever be more turbulent than being employed as a censor, the Hays Code was promptly disregarded and forgott- actually, no it wasn't. Suprisingly, this retarded system survived for over 30 years, until 1968 when Jack Valenti, head of the now-MPAA (it was renamed in ****), decided that censorship didn't really work in the hippy years and released the first group of voluntary ratings in partnership with NATO, or the National Association of Theater Owners to give them their full title.
Damn. That last part really shut down the 'mistaken identity' joke we were about to make here