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Comma misuse is a common occurrence. If a writer leaves out commas, then too much information in the sentence runs together, reducing clarity. If a writer puts in too many commas, then information that should be connected becomes separated, confusing the reader.


Understand what commas represent in writing.

The comma is a punctuation mark that is used to keep distinct information separated. It helps the reader understand how the ideas in the sentence work together.

Although many writers benefit from reading aloud commas as pauses while proofreading, a comma does not always represent a pause in a spoken sentence. When speaking, people pause for many reasons, and inserting commas at all points where you would pause often leads to misplaced commas. You are better served by learning the rules of comma usage.

Use commas to separate…

three or more items in a list.

Consultants can help you brainstorm, outline, draft, and revise a paper.

Doug, Steve, and Kai all went to the game together.

complete sentences that are combined with a coordinating conjunction: and, but, yet, so, or, nor, for.

Gary stormed out of the room, and Geri went after him.

Bob might have gone home after class, but he hasn’t been here all day.

names in direct address.

Susan and Kim, do you want to help me with my paper?

I’m not sure what to do about this problem, Matt, but you should take care of it today.

introductory phrase or clause from the rest of a sentence

Transitional phrases

First, you need to brainstorm your topic.

Nevertheless, Covey brings up several good points.

Prepositional phrases

Despite his large debt, David bought a new iPad.

During the last two months of school, Joan trained for the marathon.

Subordinate clauses

When books inspire, they achieve greatness.

Although the Minnesota Twins improved their record, their weak starting pitching still prevented them from getting to the playoffs.

Signal phrases for quotations

Saxophonist Albert Ayler has asserted, “Music is the healing force of the universe.”

“I write this sitting in the kitchen sink,” begins Dodie Smith’s novel, I Capture the Castle.

non-essential information from the rest of the sentence, such as an interruption or relative clause.

My aunt Sherri, who owns a shop in Duluth, lost $500 at a casino last weekend.

Many species of penguin, including emperors, do not mate for life.

Mary wrote an additional check, which bounced later that week.

I just returned from a trip to Denver, the mile high city.

Note: Sometimes non-essential information will include commas within it. When this happens, use dashes or parentheses to separate it from the rest of the sentence:

Louie stormed into the room and took four items off the desk—a pen, a paper clip, and two sheets of paper—before leaving in a hurry.

Some growing cities in the United States (such as Ft. Collins, CO and Eugene, OR) have tried passing laws limiting the spread of urban sprawl.

Do not use commas to separate...

subjects from their verbs if there is no non-essential information between them.

When Joe went to the party, Steve, picked up the tab.

When Joe went to the party, Steve picked up the tab.

A person with blue hair, was rollerblading down Broadway.

A person with blue hair was rollerblading down Broadway.

verbs from the rest of the predicate phrase.

I don’t think we should sterilize, people with genetic diseases.

I don’t think we should sterilize people with genetic diseases.

A commonly suggested technique for knowing where to place commas is, to read the sentence out loud and put commas in places where you naturally pause.

A commonly suggested technique for knowing where to place commas is to read the sentence out loud and put commas in places where you naturally pause.

For more information

Hacker, D. (2003). A Writer’s Reference. (5th ed.). Boston: Bedford/St. Martin’s.

Yagoda, B. (2012, June 12). The most comma mistakes. The New York Times. Retrieved from