71 Mini-Grammar Review: Commas

Dr. Karen Palmer

Commas are to readers as road signs are to drivers. Just as a driver might take a wrong turn if a sign is missing or misplaced, a reader cannot traverse a sentence meaningfully when commas are not properly in place.


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Using Commas with Introductory Words, Phrases, and Clauses

Commas set introductory words, phrases, and clauses apart from the rest of a sentence. This separation serves to signal a reader to pause and to give words a chance to have meaning without interference from other words.

  • Afterward, fans came backstage and surrounded the actors and actresses.

Using Commas in a Series

A series is a list embedded in a sentence with a conjunction, typically the word “and,” between the last two items in the list. Without the commas, a series can be quite confusing.

  • Penny’s costume included a long blue dress, a red bonnet, black lace-up shoes, a heavy gold pendant on a chain, and a very-full petticoat.

Using Commas in Compound Sentences

When a sentence is made up of two independent clauses joined by a coordinating conjunction (andbutfornor/orsoyet), a comma is needed between the two clauses. Remember that an independent clause must have both a subject and a verb and be able to serve as a stand-alone sentence.

  • Mitch arrived an hour early for the first rehearsal, and he spent the time looking through the costume closets.

Using Commas to Isolate Nonessential Words within a Sentence

To create interest and increase clarification, you may want to add words and phrases to basic sentences. These additional pieces often function as add-ons that are not essential to the core meaning of the sentence and do not change the meaning of the sentence. You should separate such words and phrases from the rest of the sentence. Some examples of nonessential words include adjective phrases and clauses, words of direct address, interjections, and appositives.

Adjective Phrases and Clauses

Some adjective phrases and clauses are essential to the meaning of a sentence and some are not. If they are essential, no comma is needed. If the meaning of the sentence would be intact if the phrase or clause were removed, a comma is needed. You can identify adjective clauses since they often begin with the relative pronouns wherewhenwhichwhowhomwhose, or that.

  • To Kill a Mockingbird, which was Malik’s first play, lasted almost two hours.

A comma is needed because, even without the adjective phrase, the reader would know that the play lasted for two hours.

Words of Direct Address

Some sentences name the person being spoken to. A person’s name that is used in this way is called a noun in direct address. Since naming the person does not change the meaning of the sentence, you should separate such a name from the rest of the sentence.

  • Your performance, Penny, was absolutely amazing!


Some words interrupt the flow of a sentence but do not actually change the meaning of the sentence. Such words are known as interjections and should be set apart from the rest of the sentence with commas. Aside from “yes” and “no,” most interjections express a sudden emotion.

  • Yes, I am going to the Saturday matinee performance.
  • I suppose you will think it is a problem if I don’t arrive until a few minutes before the curtain goes up, huh?
  • There is a chance, drat, that I might miss the first few minutes.


Appositives are nouns or noun phrases that restate an immediately preceding noun or noun phrase.

  • Malik’s first play, To Kill a Mockingbird, had six performances.

Using Commas with Coordinate Adjectives

You should place a comma between coordinate adjectives that are not joined with the word “and.” Coordinate adjectives are double adjectives and can be joined with the word “and,” rearranged, or both and still work fine.

  • Atticus is a good role for Malik since Malik is a tall, stately guy.

Do not use commas between cumulative adjectives. Cumulative adjectives build on each other, modify the next one in line, and do not make sense if rearranged.

  • Atticus Finch is a dedicated defense attorney.

This is a cumulative adjective situation because it would not work to rearrange the adjectives to say “defense dedicated attorney” or “dedicated and defense attorney.” Therefore, no commas are needed in this example; the adjective “defense” modifies “attorney” and the adjective “dedicated” modifies “defense attorney.”

Using Commas with Dialogue and Direct Quotations

You should use a comma prior to or just after the quotations in dialogue. Also, use a comma before a direct quotation when preceded by a verb such as declares, says, or writes.

  • Comma before dialogue: Jem said, “There goes the meanest man that ever took a breath of life.”
  • Comma after dialogue: “The one thing that doesn’t abide by majority rule is a person’s conscience,” said Atticus Finch.
  • No comma needed before or after a direct quotation that is not preceded by a verb: According to Miss Maudie Atkinson, Atticus “can make somebody’s will so airtight you can’t break it.”

Dates, Addresses, Geographic Names

When a date is written in month–day–year order in isolation, you need to use a comma between the day and year.

  • December 25, 1962

When a date is written in month–day–year order within a sentence and does not fall at the end of the sentence, you need to use a comma between the day and year and between the year and the rest of the sentence.

  • On December 25, 1962, the movie To Kill a Mockingbird opened in theaters.

When an address is written within running text, commas are needed between the city and state as well as between each of the “lines” of the address and between the address and the rest of the sentence if the address does not fall at the end of the sentence.

  • Annual performances of To Kill a Mockingbird are performed in the Old Courthouse Museum, Courthouse Square, 31 N. Alabama Ave., Monroeville, AL 36460, near where author Harper Lee grew up.

Use a comma after each item within a place name when the place name is used in running text, even when it is not part of a complete address.

  • Atticus Finch lived and worked in the fictitious city of Maycomb, Alabama, which many assume is patterned somewhat after Monroeville, Alabama, where the author grew up.

Company Names

Company names that include “incorporated” or “limited” (or the like) require a comma between the name and “Inc.” or “Ltd.” only when a comma is placed there as part of the official company name. Check for letterhead or the company’s website for clarification on its preferred usage.

When “incorporated” or “limited” is part of a company name within a sentence, a comma is needed between the word and the rest of the sentence only when a comma precedes it.

  • Citigroup, Inc., is making some noise in the banking industry lately.
  • Invesco Ltd. started out slowly in that sector of the market.

Titles That Go with Names

Use commas to set off descriptive titles that follow names. However, don’t use a comma before “Jr.” or “III” (or the like) unless you know the person prefers a comma.

  • Atticus Finch, attorney-at-law
  • John Hale Finch, MD
  • Walter Cunningham Jr.

Within text, include a comma both before and after the descriptive title to set it off from the whole sentence.

  • Atticus Finch, attorney-at-law, at your service.


In numbers with more than four digits, begin at the right and add a comma after every third digit. In a four-digit number, a comma is omitted in page and line numbers, addresses, and years, and it is optional in other cases. No commas are used in numbers with less than four digits. Numbers are treated exactly the same when used in text.

Using Commas to Avoid Confusion

Sometimes you simply have to use a comma to avoid confusion. For example, when a word is removed for effect, a comma can sometimes make up for the missing word.

  • To perform is a skill; to transform, art.

When two like or nearly like words are placed side by side, a comma can sometimes help clarify the intended meaning.

  • The whole cast came walking in, in full costume.

Sometimes you will need to use a comma so the reader understands how the words are to be grouped to attain the author’s desired meaning. Read the following example without the comma and note the difference.

  • Fans who can, come each year to see the annual To Kill a Mockingbird performance.

Content slightly modified from “Using Commas Properly” by Saylor Academy and licensed under CC BY NC SA.


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Mini-Grammar Review: Commas Copyright © 2023 by Dr. Karen Palmer is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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