Guidelines for Using Commas Effectively

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." But when do we need to flash that light, and when is it better to let the sentence ride on without interruption?

Here we'll consider four main guidelines for using commas effectively. But keep in mind that these are only guidelines, not ironclad laws.

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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:

    (Arthur C. Clarke, 2001: A Space Odyssey, 1968)
    (Theodore Roosevelt, "The Strenuous Life," 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."
    (John Cheever, "The Country Husband," 1955)

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

Jimmy rode his bike and Jill walked.


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


  • "You get injected, inspected, detected, infected, neglected, and selected."
    (Arlo Guthrie, "Alice's Restaurant Massacree," 1967)
  • "Walking at night, sleeping by day, and eating raw potatoes, he made it to the Swiss border."
    (Victor Hicken, The American Fighting Man, 1968)
    (Mark Twain, Following the Equator, 1897)

Notice that in each example a comma appears before (but not after) the conjunction and. This particular comma is called the serial comma (also known as the Oxford comma), and not all style guides require it. For more information, see What Is the Oxford (or Serial) Comma?

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:

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Use a Comma After an Introductory Word Group


  • "At the front of the room, a man in a tuxedo and a light-up bow tie played requests on his portable keyboard."
    (Brad Barkley, "The Atomic Age," 2004)
    (John Updike, Self-Consciousness, 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:

"At first I thought the challenge was staying awake, so I guzzled venti cappuccinos and 20-ounce Mountain Dews."
(Rich Lowry, "The One and Only." National Review, August 28, 2003)
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Use a Pair of Commas to Set Off Interruptions


  • "Words are, of course, the most powerful drug used by mankind."
    (Rudyard Kipling)
    (Bill Bryson, The Life and Times of the Thunderbolt Kid. Broadway Books, 2006)


(Samuel Johnson)

Also see the discussion of restrictive elements and nonrestrictive elements at Building Sentences with Adjective Clauses.

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Your Citation
Nordquist, Richard. "Guidelines for Using Commas Effectively." ThoughtCo, Mar. 28, 2017, Nordquist, Richard. (2017, March 28). Guidelines for Using Commas Effectively. Retrieved from Nordquist, Richard. "Guidelines for Using Commas Effectively." ThoughtCo. (accessed April 25, 2018).