... you're browsing through the book aisle at a local department store with your teenage son and he's scanning the front and back covers of a novel, a look of genuine confusion on his face.  When you ask what he's searching for, he says, "Where on a book do you find its rating?  Is this one like PG or PG-13?  How do I know if it's appropriate for me to read?"

Excellent question, son!  Maybe you should refer to this awesome book blog I know of called Bloggin' 'bout Books.  Perhaps you've heard of it?

[Image from Wikia.com]