More questions - (I hope they will be considered on-topic)
I didn't know that forums were given ratings - I thought the reader just sort of had to figure it out on his/her own. (Although I did bump into one or two that said "must be 18 to view" - and then one had to sign in.) I backed away from those because I didn't want to leave a footprint there.
It's also scary to know that someone/technology can "track" where one has been looking.
Who rates a Forum? What are the categories? Are they similar to movie ratings?