USE THE COMMA ( , )
To separate items in a series.
- (series of words) – Catholics, Protestants, Jews, and Muslims were all represented.
- (series of phrases) – She kissed him on the nose, on both eyes, and on the left ear.
- (series of clauses) – They came to the party, they bothered everyone, and they refused to leave.
*Special note: Some style guides and instructors will suggest leaving out the last comma in a series: Catholics, Protestants, Jews and Muslims were all represented.
To set off all types of nonrestrictive elements (where the information is not necessary to the meaning of the core sentence).
- Boston, the site of the famous Tea Party, is a very old city.
- The stream, once swift and clear, is now dry.
- John, who knows everything about physics, can’t change a spark plug.
*Special note: Do not put commas around essential (restrictive) information: The woman who is sitting four seats to the left is stealing donuts. [The location of the woman is essential information].
To set off introductory elements.
- When you get out of school, come over to my house.
- Feeling tired and defeated, the Senator curled up with his teddy bear.
- In the back of the house, you will find all you need to know about the crime.
Before a coordinating conjunction (for, and, nor, but, or, yet, so) when used to connect main clauses.
- We visit them during Christmas vacation, and they visit us every summer.
- The batter swung at the ball three times, but he never came close.
*Special note: Do not use a comma if your coordinating conjunction connects a main clause and a dependant clause: The batter swung at the ball three times but never came close.
To connect free modifiers to a base sentence.
- The jockeys sat bowed and relaxed, moving a little at the waist with the movement of their horses.
- A few hours later we caught two small dolphins, startlingly beautiful fish of pure gold, pulsing and fading and changing color.