Oxford commas are great at preventing misunderstanding. One of my students sent me a news report on a court case filed on behalf of some workers who thought they deserved overtime. The issue? The lack of an Oxford comma.
So, what is one, you might ask? An Oxford comma is used between the last item in a list of things and the second-to-the-last item. Here are some examples of when they are used and when they are left out:
I love my parents, Donald Duck and Daisy Duck. (Your parents are a couple of ducks, which automatically makes you quackers.) To verify that you are talking about three separate individuals, use an Oxford comma: I love my parents, Donald Duck, and Daisy Duck.
I want to leave my 3 million dollars to my children: Child A, Child B and Child C. Child A gets 1 1/2 million; Child B and Child C split the other 1 1/2 million dollars. With the Oxford comma, the sentence reads: I want to leave my 3 million dollars to Child A, Child B, and Child C. Everyone gets one million and all are happy. [Note to my children: I named you with regular names, but sadly do not have 3 million dollars to leave you. Enjoy your names, ’cause there isn’t much else to get!]
I hope this helps!