Use of the comma, semicolon, and colon

Use of the comma

RULES: The comma is the most often used mark of punctuation within a sentence. Study its use carefully.Use a comma to separate independent clauses connected by a coordinating conjunction, (and, but, or nor, yet, and for)

For example: John became very uneasy, for he was lost in the vast forest. We did not see any Indians in the Everglades, nor did we meet any tourists.


Use commas to set off she said, he replied, and similar expressions from direct quotations.

For example: She said, “We will see you this afternoon.” “I run as fast as I can.”


Use commas to indicate omissions.

For example: Henry will go to Harvard; Helen, to Vassar.


Use commas to separate a series of three or more coordinate words, phrases, or clauses, Always use a comma before etc. at the end of a series.

For example: I often saw him on the street, at church, in the post office, at ball games, and in his office.
Pens, ink, paper, etc. will be provided.


Use commas to set off words used in direct address.

For example: I am sure, Mr. Smith, that your son will win the first prize.


Use comma after a mild interjection.

For example: “Oh, perhaps there is no danger,” he said.


Use commas to set off dates and geographical expressions.

For example: He moved to 201 Cedar Avenue, Portland, Oregon, on Monday, October 1, 1963, and returned 2 months later.


Use a comma after an introductory clause or phrase when the clause or phrase is long or may be misunderstood.

For example: As I entered the door of the little house we boys had built, I saw John hide behind his desk. While looking for my book,
I found an old slipper I had lost years ago.
In the early light of dawn, we often feel more optimistic than we do at 6:00 o’clock in the evening.


Use commas to set off appositives not closely connected with the meaning of the sentence.

For example: Bill, who is the captain of our team, is the brother of Lawrence, a member of my high school class.


Use commas to set off initials or titles following a personal name.

For example: Professor H.A. Brown, Ph.D., talked to us today.
Smith, T.B., and Stone, F.M., are absent.


Use commas to set off any parenthetical or inserted matter in the sentence.

For example: The boys, however, had rather go fishing. I will go, of course, if you insist.


Use commas to set off non-restrictive words, phrases, and clauses. Do not use commas to set off restrictive modifiers.

For example: Computers, which are found almost everywhere, have become necessary to modern life. (Non-restrictive clause)
Computers that have crashed are useless. (Restrictive clause)


Use of the Semicolon

Use a semicolon between two clauses of a compound sentence when they are not joined by a conjunction unless they are very short and are used informally:

The rain came in torrents; we did not know what to do. (This may be punctuated as two sentences.)
He came, he saw, he went away. (Main clauses are short; hence, commas can be used.)


The semicolon is used between clauses of a compound sentence which are joined by conjunctive adverbs, such as therefore, hence, however, nevertheless, accordingly, on the other hand, thus, then:

The day was very cold; therefore, we did not go for a ride.
I had studied every night this week; consequently, I did well in Biology 1010.


The semicolon is often used between clauses which are joined by conjunctions if the clauses are long, or if the clauses have commas within the group of words, phrases or clauses set off by commas:

John arrived last night, I am told; but because his plane was late, he could not come to the party.
We invited Don Webb, the captain of the team; Sue Mills, the president of our class; and Joe Wynn, the chairman of our group.
We invited the following members of the orchestra: John, a clarinetist; Sue, a bassoonist; Maria, a percussionist; and LeFay, a cellist.


The semicolon usually precedes as, namely, or thus when used to introduce examples:

Four boys were mentioned; namely, Henry, Clarence, Merle, and Clyde.


Use of the Colon

The colon is used to introduce formally a word, a list, examples, a statement or question, a series of statements, or a long quotation. An expression such as as follows or the following usually precedes the list:

He brought the following fruits: apples, peaches, nectarines, bananas, plums, cherries, and pears.


A colon is used to introduce the subtitle of a book or article:

Humor and Laughter: Theory, Research and Applications
“A World of New Questions: From ‘Why?’ to ‘How?’


A colon suggests a balance, a symmetry, or an equivalence between items on either side of the colon:

In order for Dixie to gain permission to offer four-year degrees, the administration must convince three groups: the Board of Trustees, the Board of Regents, and the Utah State Legislature.


A colon is used after the salutation of a business letter and is used between the parts of a number denoting time:

Dear Sir:
He came at 6:15 this morning.