Sometime in the 1950's some quack of a shrink went to juvenile prisons and interviewed the kids asking if they read comic books. The vast majority 0f those incarcerated did. He did not go outside of the prisoned teens.
Comics at that time were mostly Scary storys, Tales of suspense, dealing with the macabre.
This shrink went on to write a book 'Seduction of the Innocent' and appeared before the Senate Subcommittee on Juvenile Delinquency looking to censor such books.
The Comics Code Authority (CCA) was formed by the publishers to regulate thier industry.
At one point the now well known comic book writer Marv Wolfman was not able to put his name in the first page credits as it went against the code. His comic book company petitioned the CCA and got that allowance.
As with any rule, law or regulation the industry found ways around the code. As they could not mention Satan, or Zombies they came up with a caracter named Mephist0 and zuvembies.
Good ole' Stan Lee wanted to do an Anti-Drug comic in 1971. Due to the codes black and white rules they were not able to approve the comic. Stan went on to publish the comic without the CCA seal and while it was a big deal for the industry the average comic buyer did not notice.