1. To denote a directive from its target: Put that shirt on, Joshua. has a very different meaning from Put that shirt on Joshua.
2. With an adverbial clause: Although Cara hated cats, she nuzzled the kitten’s furry black face. OR Because I’m failing English, my mother’s making me go to summer school.
3. To differentiate a clause that conflicts the statement: Irene’s allergic to strawberries, not raspberries.
4. To set off a non-restrictive clause (aka “which”): The Leaning Tower, which is located in Pisa, is a major tourist attraction.
5. To separate a list of items or adjectives: Lisa tossed romaine, sliced tomatoes, mushrooms, and carrot curls into a salad bowl. OR Travis was tall, lean, and rugged with dark hair, light eyes, and a hint of stubble on his cheeks.
Here’s the tricky part: Many writers will leave off that last comma (before “and”). Old dogs (like me) and Catholic school grads have heart palpitations at the very idea. Why? Because, for us, that last comma denotes the last item. Without it, the last two items become one entity. The buffet held shrimp, fried chicken, spaghetti, and macaroni and cheese. You wouldn’t separate macaroni and cheese, but if you switched the sentence around: The buffet held shrimp, macaroni and cheese, fried chicken and spaghetti. Fried chicken and spaghetti have become one entity, like the macaroni and cheese.
Lucky for you youngsters, the rule isn’t quite so stringent anymore. So if you prefer to forgo the last comma, despite my stellar example here, that’s your choice. Just be consistent throughout your manuscript! And be flexible if your editor/agent wants you to change your mind.
That concludes this week's grammar lesson. Don't forget to visit the other Friday Five gals. Their links are in my sidebar.