commas

(pdf)

Problem

Comma misuse is a common occurrence. If a writer leaves out commas, then too much information in the sentence runs together and the writing will lack clarity. If a writer puts in too many commas, then information that should be connected becomes separated and the writing will confuse readers.

Solutions

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 placing commas in 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 Gary 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.

• Signal Phrases for Quotations
  • My writing consultant says, “Correct comma usage is important for reader understanding.”
  • “No,” sighed Lisa. “I really don't want to go to a movie tonight.”
      
• 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 iPod.
  • During the last two months of school, Joan trained for the marathon.
      
• Subordinate Clauses
  • When books inspire, they achieve greatness.
  • Although Jenna was confused by the advice she was given, she followed the plan.

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.

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

Wrong:   
A girl with blue hair, was rollerblading down Broadway.
Correct:  
A girl with blue hair was rollerblading down Broadway.

verbs from the rest of the predicate phrase.

Wrong:   
I don't think we should sterilize, people with genetic diseases.
Correct:  
I don't think we should sterilize people with genetic diseases.

Wrong:  
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.
Correct:
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, Diana. A Writer’s Reference. 5th ed. Boston: Bedford/St. Martin’s, 2003. 235–250.