Comic Code Authority is the set of guidelines that publishers are allowed to use help stay within the public's interest.

My personal feeling is that there are some comics that have a lot of violence, sex, as well as foul language that go outside what most parents with very young children would want. The comics that Marvel or DC Comics though, very rarely show sex or dirty slang. Even though these two companies also have some fighting they are not violent because they do show people getting stabbed or excessive blood. Instead it's more like good guys with cool looking "super-powers" fighting those that are "evil" because they threaten the Earth or humanity.