Look, Charlie, it's the Grammar Brigade! That's right; we often forget the importance of grammar in our hurry to get the story across. But good grammar does make a difference. Bad grammar is one of my pet peeves (just ask anyone I've edited,) so I'll be putting up the occasional lesson for frequently forgotten rules.
Today's topic: Commas in addressing people. I frequently see writers forget to set names off with commas. This makes a difference. Consider:
Fly to the North James.
Huh? Where is "North James"? Is that a city?
Oh, you mean: Fly to the North, James. As in, James the character should be flying North.
When directly addressing a person, set off their name with a comma.
Nora, look out! The Grammar Brigade is out to get you!
Don't worry, mom; it's not as bad as it looks. (Note: "Don't worry" is a complete clause. If you add anything else, you'll usually need a semi-colon. This is another common mistake.)
In all of these cases, the name is a way to identify to whom the sentence is addressed. "Luke walked to the store" does not need a comma, because you're not directly addressing Luke. "Cherry, Luke walked to the store" does need a comma - you're informing Cherry that Luke walked to the store; thus, you are directly addressing her (and she probably just asked where Luke was, at the same time that Sally asked where her shoes were.)