At Major Spoilers we believe in the Oxford comma, and you should, too.
Anytime you have a list of more than two things in a sentence, there should always be a comma before the “and” ahead of the last item in the list.
For example:
INCORRECT
I would like to thank my parents, Oprah and Obama for all the help they have provided.
CORRECT
I would like to thank my parents, Oprah, and Obama for all the help they have provided.
INCORRECT
For lunch I had a peanut butter and jelly sandwich, a bag of chips and a soda.
CORRECT
For lunch I had peanut butter and jelly sandwich, a bag of chips, and a soda.
How many Power Rangers are there?
Rangers Red, Blue and Yellow. This implies there are two Rangers – Ranger Red, and Ranger Blue and Yellow.
Rangers Red, Blue, and Yellow. This implies there are three Rangers – Ranger Red, Ranger Blue, and Ranger Yellow.
In short, The Oxford Comma – Learn it, Live it, and Love it.