Did you know that editors use style guides when editing a piece of work. What they are editing and who they are editing for can both determine what style guide they will use. I use the Chicago Manual of Style – commonly used for fiction – and the AP (Associated Press) Style Guide – commonly used for news print and web news. Companies often create their own style guides so that all the copy that leaves a particular company looks the same and so the staff don’t throw things at each other over punctuation and grammar arguments. (Really, it could happen!)
Andrew Doty and Amy Lorenti will give you some inside poop on style guides, if really want to know.