What Is an Oxford comma? Importance & Examples

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Danielle McLeod

Danielle McLeod is a highly qualified secondary English Language Arts Instructor who brings a diverse educational background to her classroom. With degrees in science, English, and literacy, she has worked to create cross-curricular materials to bridge learning gaps and help students focus on effective writing and speech techniques. Currently working as a dual credit technical writing instructor at a Career and Technical Education Center, her curriculum development surrounds student focus on effective communication for future career choices.

The Oxford comma is a punctuation mark whose use is hotly debated among certain English language writers, reporters, teachers, and academics. The use, or lack thereof, of the Oxford comma may cause confusion, depending on the circumstance, which is why I am such a proponent of its use.

Afterall, it is better to be safe than sorry when you want your reader to understand what point you are trying to make, correct?

Let’s examine the definition of this controversial comma, how it got its name, who was the first to encourage its use and some examples of its use in sentences.

What is an Oxford Comma?

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An Oxford comma is used before the coordinating conjunction in a sentence that includes a list of three or more items. For this reason, an Oxford comma is also known as a serial comma and is part of a heated debate concerning the necessity of its use between grammar purists and technical academics. 

Grammar rules state that only the comma that appears before the coordinating conjunction is known as the Oxford comma. 

For example:

  • The four seasons are spring, summer, fall and winter.
  • The four seasons are spring, summer, fall, and winter.

In this instance, the Oxford comma appears in the second sentence after the word “fall.” The meaning does not change depending on the use or omission of the Oxford comma.

Let’s look at an example in which the use of the Oxford comma does matter:

  • I dedicate this book to my parents, Ayn Rand and God.

Leaving out the Oxford comma creates confusion, indicating that Ayn Rand (a famous writer I highly recommend) and God are the author’s parents. And the book is dedicated to them. This is a great example of a persuasive argument in favor of its regular use. 

Let’s add an Oxford comma for clarity and see what it does:

  • I dedicate this book to my parents, Ayn Rand, and God.

The Oxford comma helps clear up confusion and makes it known that the author is dedicating the book to their parents, the author Ayn Rand, and God.

The Oxford Comma Rule

The Oxford comma follows the rules of commas in lists and is used to separate the final two items of a list that contains three or more items. It is always placed before the final coordinating conjunction.

Commas are used between words, phrases, and clauses in a list to allow your reader to understand they are separate from one another.

When Not to Use Commas

Commas are not needed when there are only two items in a list or when conjunctions already separate the single items in a list.

For example:

  • I picked up paper plates and plastic cups and spoons for the party.

Oxford Comma Examples

The addition of this simple comma ensures that your list items are always separated and helps avoid any potential ambiguity and confusion your reader could possibly have. 

  • I’ll pick up the food for lunch, milk, coffee, and juice for tomorrow’s stay at the camp.
  • The soccer team won due to the player’s focused determination, their hard work, and the coaching staff that never quit on them.
  • Her old career was riddled with meetings that could have been emailed, paperwork that was never used for anything, and poorly trained leadership.

Oxford Comma Origins

Originally attributed to the leader in the print industry in Venice, Italy during the 1500s, the serial comma can be seen used in many listed items during that time period.

Yet, the Oxford comma is so named because its use was heavily encouraged by men working for the Oxford University Press, first introduced in Horace Hart’s book Rules for Compositors and Readers in 1905. The book served as a style guide for the Oxford University Press, which included using a comma before a coordinating conjunction.

However, the name “Oxford comma” wasn’t used until 1978, when the term was published in the book The Oxford University Press: An Informal History.

Today, whether or not one uses the Oxford comma depends on the style guide that one follows. Generally, journalists do not use the Oxford comma, while academics tend to favor its use to avoid ambiguity in their writing.

Choose whether or not you will use the Oxford comma in your document and be consistent. The correct usage of the Oxford comma is considered necessary in technical and academic situations.

Does AP Style Use an Oxford Comma?

The AP Style Guide was designed for journalists and similar communicators and was based on the original newspaper print that highly valued each space. Because of this, the Oxford comma is often avoided in newsworthy print unless it is absolutely needed for clarity.

Unlike my advice, which is to choose whether to use it or not and stick to a consistent plan, the AP Style Oxford comma rule says you can pick and choose when it should be used. It is acceptable to use when a sentence is particularly complex, or list items already include a conjunction.

Personally, I think you should always use it to avoid confusion before it becomes a thing.

Let’s look at some example sentences of when an Oxford comma isn’t needed:

  • I had bacon, eggs and toast for breakfast.
  • Please pick up milk, juice and butter at the store.
  • My classmates, Jennifer, Andrea and Michael all took the SAT on the same day I did.

Let’s look at some examples of why an Oxford comma is an important punctuation mark:

  • I had bacon and eggs, toast and butter, and juice and coffee for breakfast (without the comma, your sentence would be rambling).
  • The school offered courses in advanced astrology, mathematics, and physics (without the comma, one might think the courses are over astrology mathematics and astrology physics – not separate classes).
  • I need you to pick up Sarah, the musician, and the caterer since I have run out of room in my vehicle (without the comma, it is implied that Sarah is the musician and caterer).

Let’s Review

Although there are disagreements surrounding the Oxford comma debate, most academics agree that it should be used consistently to help keep lists from becoming confusing. Also known as the serial comma, the Oxford comma is placed between the last words, phrases, or clauses in a list of items and is placed before the coordinating conjunction.

The biggest argument in it’s favor works to keep items in the list from becoming confusing or jumbled, and should be used constantly.