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.

■Semicolon

Use a semicolon to join 2 independent clauses when the second clause restates the first or when the two clauses are of equal emphasis.

Road construction in Dallas has hindered travel around town; streets have become covered with bulldozers, trucks, and cones.

Use a semicolon to join 2 independent clauses when the second clause begins with a conjunctive adverb (however, therefore, moreover, furthermore, thus, meanwhile, nonetheless, otherwise) or a transition (in fact, for example, that is, for instance, in addition, in other words, on the other hand, even so).

Terrorism in the United States has become a recent concern; in fact, the concern for America’s safety has led to an awareness of global terrorism.

Use a semicolon to join elements of a series when individual items of the series already include commas.

Recent sites of the Olympic Games include Athens, Greece; Salt Lake City, Utah; Sydney, Australia; Nagano, Japan.

■Colon

Use a colon to join 2 independent clauses when you wish to emphasize the second clause.

Road construction in Dallas has hindered travel around town: parts of Main, Fifth, and West Street are closed during the construction.

Use a colon after an independent clause when it is followed by a list, a quotation, appositive, or other idea directly related to the independent clause.

Julie went to the store for some groceries: milk, bread, coffee, and cheese.

In his Gettysburg Address, Abraham Lincoln urges Americans to rededicate themselves to the unfinished work of the deceased soldiers: “It is for us the living rather to be dedicated here to the unfinished work which they who fought here have thus far so nobly advanced. It is rather for us to be here dedicated to the great task remaining before us — that from these honored dead we take increased devotion to that cause for which they gave the last full measure of devotion — that we here highly resolve that these dead shall not have died in vain, that this nation under God shall have a new birth of freedom, and that government of the people, by the people, for the people shall not perish from the earth.”

I know the perfect job for her: a politician.

Use a colon at the end of a business letter greeting.

To Whom It May Concern:

Use a colon to separate the hour and minute(s) in a time notation.

12:00 p.m.

Use a colon to separate the chapter and verse in a Biblical reference.

Matthew 1:6