Some people put a comma before 'and' in citations or texts.
Jan Mees, Jan Seys, and Eric Coppejans
My friend, my sister, and my son
It is always best to have consistency when writing, so I always use the serial comma. Though sometimes a sentence is easily understood without it, as in your first example, there are other times that can get confusing. If you only use it some of the time, the reader cannot always be sure what you mean.
I am going to lunch with John, an attorney and a musician. This indicates that you are having lunch with one person who is both an attorney and a musician.
I am going to lunch with John, an attorney, and a musician. You will have lunch with three different people.
|link comment||edited Nov 19 '12 at 20:19 Patty T Grammarly Fellow|
Hero of the day
Person asked the most questions.