COMMAS: The THIRD and LAST set of rules…
1) Use commas to set off elements that interrupt the sentence, like “side remarks.”
Ali slipped into class, late as usual, and sat down.
Ranchers, for example, worry about black bears in the forests.
I made popcorn, of course, to eat while watching the film.
2) Set off words used for direct address with commas.
Come over, Joe, and have dinner with us.
I am going to the store, Mom.Go here to practice:http://www.ixl.com/ela/grade-8/commas-in-direct-addresses-introductory-words-interjections-and-interrupters