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The Comma Rules - Comma Grammar & Punctuation Examples

Commas can be some of the most confusing punctuation to work with, and no one understands that more than the editors at Dog Ear Publishing. In this article, we’re going to cover some of the rules as painlessly as possible!

First, let’s look at the conjunction. Conjunctions are words like and, or, but, yet, and so. When combined with commas, they link words, sentences, phrases, and/or clauses together.

Commas with Conjunctions

#1 To link items in a series, a conjunction (usually or or and) is used alongside a serial comma, which separates the items.

  • The sun descended, touched the horizon, and disappeared.
  • She was fond of varying shades of blue, especially azure, cerulean, and turquoise.
  • The party guests include John, Matilda, and Paul and Helen, who are rarely seen apart.
  • Trina thought Burton was tall, lanky, and gorgeous.
  • You can have your choice of pizza, salad, cheeseburger, or hamburger for lunch.

#2 A comma is used before the conjunction to link two complete sentences (independent clauses).

  • Ann was an avid reader, and her nose was always in a book.
  • Are you looking to adopt a dog, or would you prefer a cat?
  • He wanted to sketch, but his favorite pencil was nowhere to be found.
  • The movie ended early, so they decided to go for a walk.

#3 If the word or phrase following a conjunction cannot stand on its own as a sentence, no comma is used before the conjunction.

  • She ordered tea and honey.
  • The dog fetched the bone and then buried it.
  • Do you prefer roses or violets?
  • He felt shy but curious.

Next, let’s focus on introductory phrases, clauses, and words. Because these introductions are not complete sentences in and of themselves, commas are used to link them to the main sentence.

Commas with Introductory Words

  • Although the clock was ticking loudly, he took his time.
  • Because it was hot outside, they decided to see a movie instead.
  • In the event of an emergency, head toward the nearest exit.
  • On the other hand, she couldn’t think of a reason not to.
  • Well, he would just have to try harder next time.

Commas are also necessary to set off interrupters, those little nonessential asides that break into the middle of a sentence. A comma is used on either side to link the broken pieces together.

Commas with Interrupter Words

  • They would, indeed, give it a chance.
  • It was, in fact, an interesting change of pace.
  • He knew, sadly, that he would never have the courage to speak up.

In fact, any word, clause, or phrase that is not essential to the meaning of a sentence should be enclosed by commas.

  • His version of fun, however, did not connect with hers.
  • The dog, who was listening intently, cocked his head to one side.
  • My sister, a world-class pie maker, is coming to town.

Finally, we come to more conventional, everyday uses of commas.

#1 In dates, commas are used between two sets of numbers placed back to back (as in the date and year, but not between the month/season and year)

  • Patricia’s diary ended on February 17, 1854.
  • Abraham Lincoln was shot on April 14, 1865, at Ford’s Theatre.
  • She was born in March.
  • On Christmas Day, we began a new tradition.
  • When written in the formal European style, today’s date is 18 May.
  • They tabled the topic for their next meeting in summer.

#2 In addresses, commas are used between the elements of the address: (1) street number and name, (2) apartment/suite number, (3) city, (4) state and ZIP.

  • She lives at 394 Willmont Way, Piedmont, CA 94620.
  • She moved there from 7291 Main Street, Huntington Beach, California.
  • Chicago, Illinois, is a bustling city.
  • We traveled to Portland, Oregon, on a whim.

#3 Commas are used to set off titles and degrees used after a name, but they are not used with elements considered part of the name (such as Jr., Sr., II, III).

  • Robert Tennant Jr. was a concert pianist.
  • Robert Tennant III chose the guitar instead.
  • Alicia Walker, PhD, went on to become the president of Harvard Business School.

We hope this article has shed some light on the often-asked questions of where and when to place commas. If you’d like to delve further into the fascinating subject of comma placement, we recommend The Chicago Manual of Style (16th Edition). It’s our go-to guide. (You can purchase it in book format or subscribe online for access to a Q&A forum and easy-to-use search box.)