What is the Oxford Comma and how do we Use it?
What is a comma?
A comma is a punctuation mark that is used to indicate a pause in and sentence, and is also used in lists of three or more items.
What is the Oxford comma?
The Oxford comma, UK comma, or the serial comma, was originally used by editors and publishers at Oxford University Press. When a comma before a conjunction in a list, this is referred to as an Oxford Comma. For example: I bought apples, oranges, and bananas. The comma coming before the and in the example is referred to as the Oxford comma.
Although it was initially used in the UK, Most British writers believe the Oxford Comma is a waste of print, and no longer use it. Others (primarily, but not exclusively, Americans) advocate passionately for its inclusion. So followers of the Oxford comma would write: I bought apples, oranges and bananas (with no comma before and). Those who avoid using the Oxford comma would write: I bought apples, oranges, and bananas (with a comma before and).
There is, in fact, no rule. You should adhere to the conventions established by your journal. Most UK journals do not use it, while many American journals do. If your journal lacks a convention or standard rule, then it is your preference. If you are free to make your own decision, then choose a convention and be consistent in using it throughout your writing.
Breaking consistency for more clarity
However, if you are not using it, you can break this convention and strategically use it in certain cases to avoid ambiguity (clarity always trumps conventions). For example:
I watched The Avengers and Spiderman.
This sounds like one single movie called “The Avengers and Spiderman”. So to avoid this, and clarify that those are two individual movies, you can strategically use the Oxford comma. This would clarify that these are in fact two separate movies:
I watched The Avengers, and Spiderman.