Brief Overview of Punctuation

When speaking, we can pause or change the tone of our voices to indicate emphasis. When writing, we use punctuation to indicate these places of emphases. This handout should help to clarify when and how to use various marks of punctuation.

Independent clause: a clause that has a subject and a verb and can stand alone; a complete sentence

Dependent clause: a clause that has a subject and a verb but cannot stand alone; an incomplete sentence

■Comma

Use a comma to join 2 independent clauses by a comma and a coordinating conjunction (and, but, or, for, nor, so).

Road construction can be inconvenient, but it is necessary.

The new house has a large fenced backyard, so I am sure our dog will enjoy it.

Use a comma after an introductory phrase, prepositional phrase, or dependent clause.

To get a good grade, you must complete all your assignments.

Because Dad caught the chicken pox, we canceled our vacation.

After the wedding, the guests attended the reception.

Use a comma to separate elements in a series. Although there is no set rule that requires a comma before the last item in a series, it seems to be a general academic convention to include it. The examples below demonstrate this trend.

On her vacation, Lisa visited Greece, Spain, and Italy.

In their speeches, many of the candidates promised to help protect the environment, bring about world peace, and end world hunger.

Use a comma to separate nonessential elements from a sentence. More specifically, when a sentence includes information that is not crucial to the message or intent of the sentence, enclose it in or separate it by commas.

John’s truck, a red Chevrolet, needs new tires.

When he realized he had overslept, Matt rushed to his car and hurried to work.

Use a comma between coordinate adjectives (adjectives that are equal and reversible).

The irritable, fidgety crowd waited impatiently for the rally speeches to begin.

The sturdy, compact suitcase made a perfect gift.

Use a comma after a transitional element (however, therefore, nonetheless, also, otherwise, finally, instead, thus, of course, above all, for example, in other words, as a result, on the other hand, in conclusion, in addition)

For example, the Red Sox, Yankees, and Indians are popular baseball teams.

If you really want to get a good grade this semester, however, you must complete all assignments, attend class, and study your notes.

Use a comma with quoted words.

“Yes,” she promised. Todd replied, saying, “I will be back this afternoon.”

Use a comma in a date.

October 25, 1999

Monday, October 25, 1999

25 October 1999

Use a comma in a number.

15,000,000

1614 High Street

Use a comma in a personal title.

Pam Smith, MD

Mike Rose, Chief Financial Officer for Operations, reported the quarter’s earnings.

Use a comma to separate a city name from the state.

West Lafayette, Indiana

Dallas, Texas

Avoid comma splices (two independent clauses joined only by a comma). Instead, separate the clauses with a period, with a comma followed by a coordinating conjunction, or with a semicolon.

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