4 Rules for Using Commas Effectively

4 Rules for using commas

 ThoughtCo

In his essay "In Praise of the Humble Comma," author Pico Iyer compares the comma to "a flashing yellow light that asks us only to slow down," (Iyer 2001). But when do we need to flash that light, and when is it better to let the sentence ride on without interruption?

Here are the four main guidelines for making that decision and using commas effectively. Keep in mind that these are only guidelines, not steadfast rules.

01
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Use a Comma Before a Conjunction That Joins Main Clauses

As a general rule, use a comma before a common conjunction (and, but, yet, or, nor, for, so) that links two main clauses:

  • "The drought had lasted now for ten million years, and the reign of the terrible lizards had long since ended," (2001: A Space Odyssey).
  • "It is hard to fail, but it is worse never to have tried to succeed," (Roosevelt 1899).
  • "The color of the sky darkened to gray, and the plane began to rock. Francis had been in heavy weather before, but he had never been shaken up so much," (Cheever 1954).

There are exceptions, of course. If the two main clauses are short, a comma may not be needed:

  • Jimmy rode his bike and Jill walked.

In most cases, do not use a comma before a conjunction that links two words or phrases:

  • Jack and Diane sang all night.
02
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Use a Comma to Separate Items in a Series

Use a comma between words, phrases, or clauses that appear in a series of three or more:

  • "You get injected, inspected, detected, infected, neglected, and selected," (Guthrie 1967).
  • "Walking at night, sleeping by day, and eating raw potatoes, he made it to the Swiss border," (Hicken 1968).
  • "It is by the goodness of God that in our country we have three unspeakably precious things: freedom of speech, freedom of conscience, and the prudence never to practice either of them," (Twain 1897).

Notice that in each example, a comma appears before (but not after) the conjunction and. This particular type of comma is called a serial comma or the Oxford comma. It is optional and not all style guides require it.

In the following paragraph from Animal Farm, observe how George Orwell uses commas to separate main clauses that appear in a series of three or more:

"Man is the only creature that consumes without producing. He does not give milk, he does not lay eggs, he is too weak to pull the plow, he cannot run fast enough to catch rabbits. Yet he is lord of all the animals. He sets them to work, he gives back to them the bare minimum that will prevent them from starving, and the rest he keeps for himself," (Orwell 1946).
03
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Use a Comma After an Introductory Word Group

Use a comma after a phrase or clause that precedes the subject of a sentence:

  • "At the front of the room, a man in a tuxedo and a light-up bow tie played requests on his portable keyboard," (Barkley 2004).
  • "Lacking brothers and sisters, I was shy and clumsy in the give and take and push and pull of human interchange," (Updike 1989).
  • Whenever I get the urge to exercise, I lie down until the urge passes.

However, if there's no danger of confusing readers, you may omit the comma after a short introductory phrase, as Rich Lowry did in "The One and Only":

"At first I thought the challenge was staying awake, so I guzzled venti cappuccinos and 20-ounce Mountain Dews," (Lowry 2003).
04
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Use a Pair of Commas to Set Off Interruptions

Use a pair of commas to set off words, phrases, or clauses that interrupt a sentence:

  • "Words are, of course, the most powerful drug used by mankind." -Rudyard Kipling
  • "My brother, who was normally quite an intelligent human being, once invested in a booklet that promised to teach him how to throw his voice," (Bryson 2006).

But don't use commas to set off words that directly affect the essential meaning of a sentence. See this from the quote attributed to Samuel Johnson:

"Your manuscript is both good and original. But the part that is good is not original, and the part that is original is not good." -Samuel Johnson

Sources

  • 2001: A Space Odyssey. Dir. Stanley Kubrick. Metro-Goldwyn-Mayer, 1968.
  • Barkley, Brad. Another Perfect Catastrophe: And Other Stories. 1st ed., Thomas Dunne Books, 2004.
  • Bryson, Bill. The Life and Times of the Thunderbolt Kid. Broadway Books, 2006.
  • Cheever, John. "The Country Husband." The New Yorker, 13 Nov. 1954.
  • Guthrie, Arlo. “Alice's Restaurant Massacree.” Alice's Restaurant, Fred Hellerman, 1967, 1.
  • Hicken, Victor. The American Fighting Man. Macmillan 1968.
  • Iyer, Pico. "In Praise of the Humble Comma." Time, 24 June 2001.
  • Lowry, Rich. "The One and Only." National Review, 28 Aug. 2003.
  • Orwell, George. Animal Farm. Harcourt, Brace and Company, 1946.
  • Roosevelt, Theodore. 10 Apr. 1899, Chicago.
  • Twain, Mark. Following the Equator. American Publishing Company, 1897.
  • Updike, John. Self-Consciousness. 1985.