Want to rile up a bunch of editors? (Why would you? I don’t know. Just go with it.) Ask their opinion on the serial comma.
A serial comma, also known as the Oxford comma, is one that is placed before the last item in a series. In the sentence, “To make a martini, you need vodka, vermouth, and olives,” the serial comma is the one that appears after ‘vermouth’ and before ‘and olives.’
I like the uncluttered feel of a series without that final comma: “To make a martini, you need vodka, vermouth and olives.” But I’m flexible and will use it in longer sentences if I feel like the reader will trip over words without it. Other advocates of the serial comma say it better mimics conversational cadences.
Like all matters of style, it’s best to identify your preference and stick with it. Either way, you’ll be in good company. While, AP style omits the serial comma, Chicago Manual of Style, AMA and APA all require it.