There are numerous uses for the comma, and it is the most misused punctuation mark in the English language.
A comma provides a brief pause. Study the following points for correctly using the comma and listen for the brief pause in the given examples. Strengthening an “ear” for hearing this pause will help to guide you in proper comma placement.
Use commas to separate items in a list.
Could you stop at the store and buy butter, milk, lettuce and cheese?
OR
Could you stop at the store and buy butter, milk, lettuce, and cheese?
NOTE: A comma can be used before the last item to separate it and the conjunction and (as in the second example), or it can be omitted. However, you should be consistent throughout the entire text. If you use it then use it throughout. If you omit it then omit it throughout.
Use commas to separate words and word groups when there are three or more to avoid confusion.
The million dollar lottery prize will be split between Jason, Alison, Beth, and Sue.
NOTE: If the comma is omitted after Beth, it changes the meaning of the sentence. If it is omitted then Beth and Sue will split one third of the prize (instead of it being split four ways).
The million dollar lottery prize will be split between Jason, Alison, Beth and Sue.
A comma is used to separate two or more adjectives when the word and can be placed between them.
My English teacher is a tall, strong, intelligent man.
However, you would not use a comma if the word and would not be used.
His expensive new car was destroyed in the flood.
Use a comma after a name or title when starting a sentence, or surrounding it within a sentence, when a person is addressed directly.
Carmen, will you stop at the office and pick up my briefcase?
Yes, Professor, I will follow your instructions.
NOTE: Capitalize the title when addressing someone directly.
Use a comma to separate the day and the month from the year and after the year.
Julie graduated on May 5, 2007 from Haley University.
We lived in Nashville, Tennessee, for 10 years.
However, if the two letter abbreviation of the state is used, the comma is omitted after it.
We lived in Nashville, TN for 10 years.
Use commas before and after degrees or titles used with names. Commas are no longer required to separate Jr. or Sr., and they are never used to separate II, III, etc.
Andrew Whitehall, M.D., is related to Eric Stephenson Jr. and Mark Ellington II.
Use commas to separate expressions that interrupt sentence flow.
This assignment, as you can see, will be very interesting.
Use a comma after a weak clause or phrase when it begins a sentence. These are meant to follow a strong clause without a pause of interruption.
NOTE: Listen for the pause after the weaker clause. This pause is absent in the strong sentence example and, therefore, doesn’t require a comma.
STRONG: Contact me when you are ready to go to the movies.
WEAK: When you are ready to go to the movies, contact me.
STRONG: You must present the necessary documents in order to come along.
WEAK: In order to come along, you must present the necessary documents.
STRONG: We will travel to Europe on Friday.
WEAK: On Friday, we will travel to Europe.
Use commas to separate a nonrestrictive relative clause.
Mr. Johnson, who has been dancing all his life, won the national dance competition.
Use a comma to separate two clauses joined by a coordinating conjunction – and, but, or, for, nor. The comma can be omitted if the two clauses are short.
Our dog ran off into the park yesterday, and we still haven’t found him today.
I sing and she dances.
Use commas to introduce or interrupt direct quotations.
Mary said, “I don’t like you anymore.”
“Why in the world,” my mother questioned, “would you do such a thing?”
Use a comma to separate a statement from a question.
You’re going to the beach with us this weekend, aren’t you?
Use a comma to separate contrasting segments of a sentence.
Those are our seats, not yours.
Use a comma when you begin a sentence with an introductory word, such as yes, well, or now.
Yes, I should finish my homework.
Well, if you put it that way then I will have to agree.
Now, should you finish your test early then sit quietly.
Use commas before and/or after words, such as however or therefore when they interrupt a sentence.
My boss, therefore, would like for us to work next Saturday.
However, I will agree to the terms if you can guarantee a return on my money.
Use a comma (or semicolon) before introductory words, such as namely, that is, i.e., for example, e.g., or for instance.
You may be required to provide important documentation, namely a driver’s license, social security card, and birth certificate.
OR
You may be required to provide important documentation; namely a driver’s license, social security card, and birth certificate.
Use a comma in a conditional sentence that uses the word then when omitting it.
If Johnny studies very hard then he will pass Algebra.
If Johnny studies very hard, he will pass Algebra.
Should you meet Alice at the meeting then tell her I need to see her.
Should you meet Alice at the meeting, tell her I need to see her.