You Win This Round Comma

Image: man standing in comma-shaped beam of light
Photo credit: Mattiii photo on Visualhunt / CC BY-NC-SA

Today’s guest post is by author, editor and writing coach Mathina Calliope (@MathinaCalliope).

Hardly anyone would argue that commas don’t matter, but plenty of people—including plenty of writers—give them too little thought. At some point in their lives they might have tried to understand all the rules (commas to restrict information? Oxford commas? vocative commas?). They wanted to hug the English teacher who said they could simply use them “wherever you would pause if speaking.”

They went on their way, relieved to think commas were a style choice, there weren’t necessarily hard-and-fast rules, they could let an editor worry about that. Or a reader, who would be saddled with the extra mental work required to discern the author’s intended meaning.

Actually, though, you cannot just put commas where you would pause when speaking. Why? Because the presence or absence of a comma conveys meaning.

Since you’re reading this blog, you’re probably familiar with some egregious examples of comma malpractice, for example, “Let’s eat Grandma.” You know you can save a life with the vocative comma: “Let’s eat, Grandma.”

Other chuckle-worthy comma memes populate the internet, such as the picture of Stalin and JFK outfitted for pole dancing versus the one of Stalin, JFK, and two strippers (illustrating the value of the Oxford comma).

My favorite, and the most nerdy, meme is a Tumblr post with a picture of a knife blade in a block of cheese, handle broken off. The caption reads, “You win this round cheese.” The first reply: “actually that is a rectangle cheese.”

Here’s the next reply: “[oxford comma laughing in the distance].”

Then the mic drop: “[vocative comma wondering what oxford comma thinks it’s doing here].”

I know. There are A LOT of kinds of commas and a lot of rules regarding their usage. What’s more, some of these are house style points, not universal rules, and many of them can be ignored in certain situations at the discretion of the editor or writer. Finally, all may be broken deliberately for artistic effect, just as any “rule” of grammar or syntax or spelling can.

Today I’ll address just one rule, the one I see broken most often: Use a comma to show that information is nonessential (nonrestrictive); do not use a comma to show it is essential (restrictive).

Consider this sentence—

Armand gave an ashtray to his husband who smokes.

versus this one—

Armand gave an ashtray to his husband, who smokes.

What does that comma do? It changes the husband’s smoking from restrictive to nonrestrictive. What does that mean? If the information is restrictive, it limits the application to the smoking husband. In the first phrase, omitting the comma conveys that the husband we’re dealing with here is the one who smokes. The syntax implies Armand has one or more other husbands, that they do not smoke. The author doesn’t mean those husbands, he or she means this husband.

The first version isn’t wrong, IF Armand has more than one husband and IF only one of Armand’s husbands smokes. But if Armand has only one husband, the sentence says something the author does not intend it to say.

With the comma, the information is nonrestrictive. The comma signals that the important thing about the sentence is that Armand’s husband received an ashtray. It turns the information after it into extra, nice-to-know data. That information is nonessential.

Here is an example featuring bread:


The bread that I bought yesterday is stale.

Not the bread I bought today, or the day before yesterday. The phrase “that I bought yesterday” is essential; it restricts the sentence to just that loaf of bread.


The bread, which I bought yesterday, is stale.

The commas tell us there’s only one loaf of bread. That I bought it yesterday is informative but not essential, since readers just need to know it is stale.

Extra points if you noticed the “which” and the “that.” In American English, we use “which” with nonrestrictive information and “that” with restrictive information.

Here’s a coffee-related example:


Baristas who work at Starbucks make Pumpkin Spice Lattes.

Not all baristas make PSLs. Only those who work at Starbucks. (This example might or might not be true. I have not researched whether Starbucks trademarked the PSL.)


Baristas, who work in coffee shops, make cappuccinos.

We’re talking about baristas generally. They work in coffee shops—informative but not essential—and they make cappuccinos.

For better or worse, English does not have a who equivalent to the that/which distinction. (The who/whom difference is something else.)

Okay fine, you’re thinking, this comma rule really does matter. But is it that big a deal if I mess it up? Most of the time, no. Most of the time, context will help readers autocorrect the mistake and infer what you meant. Other times, getting this wrong will create ambiguity, or worse, confusion. All of the time, it creates extra work, and if part of your reader’s brain is busy trying to decode syntax-level meaning, that part of the brain cannot fall in love with your protagonist, your plot, or your prose.

If you’d rather have your reader relax into your writing, spend some time thinking about this difference. The Purdue University Online Writing Lab has some more examples, explanations, and even worksheets to help you nail this comma rule down.

And if it’s really, truly too much? Get a good editor. 🙂

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