Commas tell us how to read and understand sentences because they tell us where to pause. A correctly placed comma helps move readers from the beginning of a sentence to the end. A misplaced comma can create more confusion than a conversation with a teenager. Here are the guidelines that govern comma use.
Use a comma after introductory and concluding expressions:
- Use a comma after an introductory prepositional phrase. In each sentence, the introductory phrase is underlined.
- Example: Along the route from the house to the woods, Hansel and Gretel left a trail of old lottery tickets.
- Use a comma after an introductory participial phrase.
- Example: Excited by their approach, the witch called her agent and decided to take a meeting.
- Use a comma after an introductory subordinate clause.
- Example: When Hansel and Gretel arrived, they were astonished to find the TV contract already prepared.
- Use a comma after the greeting of an informal letter.
- Examples: Dear Sammi, Dear Mudface,
- Use a comma after phrases that show contrast.
- Example: The neighbors return home at all hours, often drunk as skunks.
- Use a comma at the close of any letter.
- Examples: Yours truly, Sincerely, Yours until Niagara falls,
Use a comma after interrupting words and expressions.
- Use a comma to set off interrupting words and expressions. The interrupting words are underlined in the following example.
- Example: Windows, as you know, is the best $89 solitaire game you can buy.
- Use a comma to set off words of direct address (words that tell to whom a remark is addressed). The words in direct address are underlined in the following example.
- Example: Mr. Happy, did you know that “kitty litter” is throwing cats out a car window?
- Use a comma with names and titles.
- Example: Mr. Gary Goldstein, Editor
- Use a comma to set off words in apposition (words that give additional information about the preceding or following word or expression). The words in apposition are underlined in the following examples.
- Example: A light sleeper, my landlord is the first to awake when he hears the chains rattle.
- Example: My landlord, a light sleeper, is the first to awake when he hears the chains rattle.
- Use a comma to set off a nonessential clause (a clause that can be omitted without changing the sentence’s basic meaning). The nonessential clause in underlined in the following example.
- Example: Philosophy, a science that lets us be unhappy more intelligently, is being offered this semester at the local university.
- Use a comma to separate items in a series.
- Example: We bought marshmallows, graham crackers, and chocolate to make those delicious campfire treats.
Use a comma to set off parts of a sentence:
- Use a comma to separate parts of a compound sentence. Use the comma before the coordinating conjunction. Remember: The coordinating conjunctions are and, but, or, nor, for, so, and yet. The coordinating conjunction is underlined in the following example.
- Example: The faucet stopped working, and the sink leaks.
- Use a comma to set off a direct quotation.
- Example: He said, “Lawyers are the larval form of politicians.”
- Example: “Lawyers,” he said, “are the larval form of politicians.”
- Use a comma to separate the parts of an address.
- Example: She lives at 763 Main Street, Farmingdale, New York 11735.
Use commas with numbers:
- Use a comma between the day of the month and the year.
- Examples: December 7, 1941, July 20, 1969
- Use commas to show thousands, millions, and so on.
- Examples: 1,000; 10,000; 100,000; 1,000,000
Now that you know the rules for commas, let’s put them to use with this quick quiz!
Add commas as necessary in the following sentences.
- Even though it is not among the top rated shows shown on a single night The Wizard of Oz is generally considered the most successful single program in TV history.
- My friend Stephan a very picky eater refuses to eat any vegetables at all.
- A child who is under the age of eight should not be left alone without a sitter.
- A mature child of 10 or 11 however can usually be trusted home alone.
- Among the top man-made attractions in the United States are the Golden Gate Bridge Mount Rushmore the Statue of Liberty and Hoover Dam.
- Let’s find a fast cheap restaurant.
- The Academy Awards were first telecast on March 19 1953.
- No you can’t pile up 10000 bricks and try to climb to the roof.
Commas may seem tricky, but they don’t have to be. Just keep these rules in mind, and you’ll also know where they go! For more grammar information, check out our Quick Guides on How to Use an Apostrophe, How to Use the Dash, Hyphen, and Ellipses, and The Rules of Capitalization. Happy writing!
From The Complete Idiot’s Guide to Grammar and Style, Second Edition, by Laurie E. Rozakis, Ph.D.