Commas seem like M&Ms—if a couple are good, a handful must be better, right?
Not so much. They’re little, but they’re powerful. And they can definitely be overused. I’ve read student papers so riddled with commas I thought some of them might actually fall off if I tipped the page.
Commas can also be underused, resulting in run-on sentences or, much worse, unfortunate altered meanings. Or, they can be totally random, inserted with no apparent rhyme or reason.
Fortunately, a few simple rules can rescue you from comma confusion. Here’s what you need to know:
1. Commas often go in pairs.
Remember the “that and which” rule about non-essential clauses? Commas surround non-essential parenthetical phrases—and that means you need two of them, one at the beginning of the phrase and one at the end.
Here’s an example:
The Opening Day Parade, in all its glory, is the official launch of baseball season.
In your writing, make sure you’re correctly setting off these phrases by using both commas.
Here’s a sneaky one: In a sentence that uses a full date, the year is a parenthetical phrase.
March 23, 2017 was a sunny day.
March 23, 2017, was a sunny day.
Sometimes the beginning or end of the sentence effectively serves as one of the commas. In those cases, one comma is fine:
Despite the cold, the children enjoyed playing outside.
Tim was happy to be part of the celebration, with or without an invitation.
2. Avoid confusion.
From non-essential clauses, we go to essential comma usage. Sometimes a tiny little comma changes the entire meaning of a sentence. Without a comma to separate a thought, the reader will put the two thoughts together—sometimes with disastrous results.
A lawsuit reported recently in the New York Times illustrates a sentence that would mean something entirely different if a comma were in place. In this case, the lack of a comma could cost a Maine company millions in overtime pay. A state law says that overtime rules do not apply to:
The canning, processing, preserving, freezing, drying, marketing, storing, packing for shipment or distribution of:
Meat and fish products; and
As written, without a comma after the word “shipment,” the sentence appears to mean that overtime rules do not apply to “packing for shipment” or “packing for distribution.” Lawyers are arguing that workers are entitled to overtime pay for the distribution of these goods—the law only appears to cover packing for distribution.
This is an example of what writers call the serial comma (also known as the Oxford comma). In its simplest form, this is what it looks like:
With the serial comma:
Red, white, and blue.
Without the serial comma:
Red, white and blue.
Old-school journalists tend to eschew the serial comma, but it has been coming back into favor lately. In general, you’re free to use either format (provided that you’re consistent) as long as that comma isn’t needed for clarity. For complicated sentences like the one above, use the comma.
3. Separate equal adjectives.
Questions often arise about how to punctuate a string of adjectives. Again, it depends upon the meaning of the sentence. If the adjectives are of equal weight and could appear in any order, use commas:
This plant grows well in warm, sunny, well-ventilated environments.
When the adjective order is important to the meaning of the sentence, it follows the rules of essential clauses:
Jim’s favorite movie is an old Western film.
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