Using Commas

Commas are one of the most essential punctuation marks in writing, but figuring out when to use them can be difficult. Here’s a guide to help you remember when to use a comma.

WHY YOU SHOULD USE A COMMA

• Commas help to clarify the meaning in sentences.
  - INCORRECT: Let’s eat Grandpa!
  - CORRECT: Let’s eat, Grandpa!
   
• Commas also make lists easier to read.
  - INCORRECT: This recipe requires milk eggs and cheese.
  - CORRECT: This recipe requires milk, eggs, and cheese. 

Use a comma

• After an introductory phrase that precedes the main clause of a sentence
  - Before Jack left the house, he locked the door behind him.
   
• With a coordinating conjunction (remember FANBOYS: for, and, nor, but, or, yet, so) in order to combine two independent clauses
  - Carol had no flour, so she couldn’t bake cookies.
   
• Between items in a series or list
  - My favorite colors are red, purple, and blue.
   
• To set off clauses, phrases, or words that add nonessential information to the sentence
  - My necklace, which my grandma gave me, fell down the garbage disposal.
   
• In dates, addresses, titles, names, and numbers
  - This overdue library book was due October 12, 2013.
   
• To set off quotations
  - Franklin Delano Roosevelt said, “The only thing we have to fear is fear itself.”

 
 
Source: Hacker, Diana. A Writer’s Reference. Boston: Bedford, 1995.