You may be thinking, “Who cares about commas?” But, for us, to comma or not to comma is frequently the question. Just look at all the commas in that last sentence…and consider the kitten image below.
The very mention of comma placement may cause an unpleasant flashback to grade school English class for some of you. Who remembers identifying the introductory clause and prepositional phrase? Both of these should be offset with commas, by the way.
The Serial Comma
Because comma usage is complicated and subject to so many rules, we’ll start with an easy, but common one: the serial comma, also known as the Oxford comma. This is the comma you place before the word “and” or “or” in a list:
I went to the store to buy eggs, butter, sugar, and flour. (serial comma)
I went to the store to buy eggs, butter, sugar and flour. (no serial comma)
Since we love punctuation, we prefer the first example (the more commas the better, right?). But, the truth is that BOTH are completely correct. With serial commas, it is simply a matter of style. More specifically, it’s a matter of style guide, and whether or not your writing requires you to follow one. A style guide is basically a rulebook for the writing and design of a document or publication.
What’s Your Style?
Style guides include the APA Style Guide, Chicago Manual of Style, MLA, and Associated Press Stylebook, among others. In addition to comma placement, each provides specific guidelines for everything from proper citation format to the appropriate use of abbreviations and capitalization. Like the Chicago Manual, MLA, and APA, we love the serial comma, but some of our clients follow the AP, which advises against them to save space.
So, which should you choose? Our recommendation is to pick the one you prefer and be consistent — especially within a single document.
That said, there are situations where omitting a serial comma makes a sentence ambiguous:
I had dinner with my brothers, the governor and the mayor.
In this example, it could be interpreted that my brothers are the governor and mayor, which they are not. Adding the serial comma indicates a list and clarifies that these are three separate entities.
I had dinner with my brothers, the governor, and the mayor.
The Bottom Line
The bottom line with serial commas — as long as your writing doesn’t require adhering to a particular style guide, simply pick the form you prefer and stick with it, remembering that a serial comma may be needed for clarity in certain sentences.
Here's a quick overview of the most common style guides and which serial comma rule they endorse.