Grammar 8 min read

Oxford Comma: Everything You Need to Know

The Oxford comma: small punctuation, big fuss. When should you use it? When should you avoid it?

Answer all of your Oxford comma questions with this simple guide.

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Main Takeaways:

  • The Oxford comma is the final comma in a serial list, used just before the conjunction.
  • It’s also known as a serial or terminal comma.
  • The Chicago Manual of Style says to always use the Oxford comma.
  • The AP Stylebook says not to use it unless necessary for clarity.

The Oxford Comma: Small Punctuation, Big Fuss

Despite its small size, the Oxford comma may be grammar’s biggest ongoing debate. This controversial punctuation mark, which separates the penultimate item in a written list from the conjunction, has left many grammarians disagreeing over its use.

The Oxford comma has been the crux of multi-million dollar lawsuits against many companies.
You may not be aware of it but the Oxford comma is so important that it became the crux of many multi-million dollar lawsuits against big companies.

What is the Oxford Comma Rule?

Essentially, an Oxford or serial comma is the final comma in a list of three or more things. It’s sometimes referred to as a terminal comma as well. This controversial comma is placed after the next-to-last item in the list, just before the and or the or.
The recipe called for some unusual ingredients, such as squid ink pasta, dry vermouth, and tomato purée.

In this example, the terminal comma is the comma that follows vermouth.

Now, before we explore this controversial comma further, let’s first understand what a comma truly is.

What is the Difference Between an Oxford Comma and a Regular Comma?

A comma is a form of punctuation that is used to organize a sentence. It lets readers know to pause and take a breath between parts of a sentence. More specifically, the comma can separate clauses, ideas, or items in lists. Conversely, an Oxford comma is the last comma in a list of three or more items.

Other Uses:

When writing out dates in month-day-year format, commas are typically used to set off the date. Commas can also be used when expressing large numbers, breaking them into three-digit blocks, so they’re easier to read.

Although a comma can add structure and clarity to a sentence, it’s one of the most misused and misunderstood forms of punctuation. Thankfully, there are some basic rules to help you understand when to use a comma.

Rules for Using Commas

By following a few simple rules, you’ll know exactly when and where to put a comma.

1. Separate Independent Clauses

Rule: Commas should be used to separate independent clauses that are linked by and, but, so, or, for, nor, and yet.
I was craving seafood, so I treated myself to a lobster at my favorite restaurant.

2. Separate Introductory Clauses

Rule: A comma should be placed after an introductory clause or phrase. Introductory clauses often begin with words such as after, although, because, before, if, since, until, and when.
When my dog needs exercise, I take her for a long walk on the beach.

3. Set Off Nonessential Phrases or Words

Rule: Use commas to set off phrases or words that are not essential to the main elements of a sentence.
I set up the dining room table, which only seats six, before the dinner party.

4. Separate Items in a List

Rule: Use serial commas to separate words or items in a list of three or more things. You may choose to use it after the penultimate item in a list or skip a comma altogether.
(Without a Comma) My shopping list included eggs, milk, bread and treats for our cat.
(With a Comma) My shopping list included eggs, milk, bread, and treats for our cat.

5. Separate Coordinate Adjectives

Rule: Use a comma to separate coordinate adjectives that describe a noun.
We experienced damp, windy conditions for days after the big storm.
The AP Style guide doesn't require the Oxford comma's use, as opposed to the Chicago Manual Style, that encourages the use of the said punctuation.
The AP Style guide doesn’t require the Oxford comma’s use, as opposed to the Chicago Manual Style, that encourages the use of the said punctuation.

6. Set Off Contrasted Coordinate Elements

Rule: Commas can set off contrasted coordinate elements near the end of a sentence.
That mistake was because of carelessness, not stupidity.

7. Separate Elements of Dates, Names, and Addresses

Rule: Use commas to set apart geographical places, titles in names, and items in dates and addresses. The latter should exclude the day and month and the street number and name.
After college, he moved to Long Island, New York. That was on June 1, 1991.

8. Separate Dialogue Tags and Quotations

Rule: Use commas between dialogue tags and quotations.
She said, “I’m taking the dog for a walk.”

9. Clarify Meaning

Rule: Use commas to prevent confusion or to clarify meaning.
She wasn’t killed, mercifully. — vs.— She wasn’t killed mercifully.

As with all things grammar, there are exceptions and clarifications to each of these comma situations. But if you follow these basic rules, you’ll rarely go wrong.

Now that you’ve got a solid grip on the comma, let’s get back to the topic at hand.

Why is the Oxford Comma Important?

It might seem hard to believe, but the placement of a simple comma can alter the meaning of a sentence. By using a serial comma in lists, you can potentially avoid misreadings and misunderstandings.

Consider this sentence:

Yesterday, Peter went to lunch with his roommates, Stephen King and a world-famous cat trainer.

Written this way, you could infer that Peter’s roommates are actually Stephen King and a world-famous cat trainer. By adding a terminal comma, the sentence becomes clearer.

Peter went to lunch with his roommates, Stephen King, and a world-famous cat trainer.

In this second example, there’s no confusion. We now understand that Peter isn’t rooming with the king of horror and the bearer of many scars. He’s just inviting them to join him and his roommates for lunch.

Not all grammarians are a fan of the controversial oxford comma.
Not all grammarians are a fan of the controversial oxford comma.

Are Oxford Commas Grammatically Correct?

Whether or not to include a serial comma is more of a stylistic choice. Some might say that Oxford commas are grammatically optional. If you’re writing for a company or organization, the using a serial comma likely depends on the style guide you’re following. For example, AP Stylebook doesn’t use the Oxford comma unless it’s absolutely essential to preserve a sentence’s meaning. On the other hand, The Chicago Manual of Style advocates for always using a serial comma. If you’re your own boss, then the ultimate comma decision rests entirely with you.

Although some people wonder if Oxford commas are grammatically correct, the answer isn’t black and white.

Why Shouldn’t you use the Oxford Comma?

Over the years, the Oxford or serial comma has had more than its fair share of detractors, many fighting fiercely against its use.

Although some grammarians believe that it can provide much-needed clarity in a written list, others argue that it’s better to just restructure the sentence.

Using the example from the last section, the sentence could easily be rewritten to clarify its meaning.

Peter went to lunch with his roommates, as well as Stephen King and a world-famous cat trainer.

With a small change of wording, the sentence becomes less confusing. This approach argues that the Oxford comma is a lazy way of solving a problem and renders it unnecessary.

Don't be a monster, use an Oxford comma!
Don’t be a monster, use an Oxford comma!

Serial Comma Meets Social Media

In 2003, Eats, Shoots & Leaves by Lynne Truss hit bookstore shelves in the United Kingdom. By 2004, it was a hit in the United States, as well.

The book title’s clever play on words and amusing panda-themed cover illustration introduced the public to the intricacies of the Oxford comma.

Ever since, people have been exploring the humorous ways that this tiny punctuation mark can change a sentence’s entire meaning.

Many examples have even found their way onto social media platforms, such as Facebook and Twitter, through memes. This viral content pairs eye-catching visuals with verbal concepts to make a statement or point. In the case of the serial comma, it’s often used to make a joke about bad punctuation.

Since its origin at the Oxford University Press, the Oxford comma has been a source of ongoing controversy. For more than a century, grammarians have argued about whether this comma is essential or should be abandoned to the annals of history.

Proponents believe that this serial comma, which belongs after the penultimate item in a list, is necessary for clarity. Detractors think it represents nothing more than an excuse for lazy writing.

Ultimately, whether they love or hate the Oxford comma, there’s one thing people generally agree on. If you’re going to use this oft-debated punctuation mark, use it consistently or not at all.

Read More: When To Use Comma Before Such As: The Definitive Guide

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