Comma Usage


The comma appears to be a harmless little fellow, but don’t let appearances deceive you. Sure, the little guy never shouts, never declares, never questions, never even finishes a sentence, but that doesn’t mean he holds no power. In fact, he is the hardest working of all the punctuation marks—the only one often appearing more than once in a single sentence. He holds the power to change the meaning of a sentence and to disrupt the flow of prose. Therefore, isn’t it time to give the little guy his due and quit misunderstanding him? Here’s his M.O.:
Use a comma to separate the clauses of a compound sentence connected by a coordinating conjunction (and, but, or, nor, for, so and yet). The comma is placed before the coordinating conjunction, not after. Example:
The students ate spaghetti for dinner, but they had no dessert.
However, do not use a comma before and, but, or and nor when they link pairs of words, phrases or elements other than main clauses. Example:
The students ate spaghetti for dinner and cake for dessert.
The trick here is to recognize whether the conjunction separates a main clause (or major thought), or if it simply links pairs of words or phrases. Writers may omit the comma in short compound sentences when the connection between the clauses is close, but it is required when linking the elements of a compound sentence. If the sentence is clearly understandable without the comma, it’s probably okay to omit it, too. Here’s an example:
Justin stood in the corner and he watched.
Use the comma to separate two or more adjectives modifying the same noun if and could be used between them without changing the meaning. Example:
Janine pushed her long, straight hair out of her eyes.
However, do not use a comma between unequal adjectives or when an adjective modifies another adjective (instead of the noun):
His coal black hair glistened in the brilliant midday sun.
The comma also separates the items in a list or a series. Example:
Jasmine visited the park, the museum, the court house, and the historical hotel on the last day of her vacation.

Note that the comma before the last item in the series (the one directly before and) is optional. Also, note that no comma appears before the first element in the list (the park), nor after the last element in the list (the historical hotel).

The comma is used in setting off transitional expressions (however, regardless, of course and so on) from the rest of the sentence. Examples:

The weight of the ball, however, was greater than the strength of the boy.
Of course, we could have eaten after they arrived.
Use the comma with introductory elements:

No, he didn’t wear a hat.

When the bell rings, the students race through the halls.

A comma sets off long phrases that precede a principal clause:
Before we could call Great Aunt Mary, we had to locate her phone number.
The comma sets off words or phrases that rename nouns. Examples:
John, my oldest cousin, loves to garden.
However, do not use a comma if the added information is essential to the meaning of the sentence, such as:
The song “Unchained Melody” melts my heart.
People who dream in color are thought to be clairvoyant.

The test is whether the sentence makes sense if the renamed noun is removed from the sentence.

A comma can indicate the omission of a word or words:

To err is human; to forgive, divine.
Use a comma to set off a word of direct address:
Thank you, Wilma, for teaching me about commas.
A comma is used to set off a quotation from a dialogue tag. Examples:

He said, “I didn’t do it.”

“I don’t believe it,” Jason replied, “but maybe if you prove it, I will.”

A comma sets off a tag question from the rest of the sentence:
I didn’t see it there, did you?
You can also use a comma to set off any sentence element that might be misunderstood if the comma were not used, such as:
To me, Millie would always be my best friend.
And finally, use a comma to set off a city from a state, the year from a full date, a series of four or more numbers, and to set off titles and degrees from surnames and from the rest of a sentence:
My children were born in Winneconne, Wisconsin.
My oldest daughter was born on November 21, 1986.
I wish my husband made $625,000 a year.
My husband’s full name is Sherden C. Tritt, Jr., although he goes by “Butch.”

As you can see, the innocuous little fellow known as the comma can be quite cantankerous. Study this little guy—once you’ve mastered him, you’ve accomplished a great feat.

For additional tips, worksheets, and discussions, order your own copy of The Plain English Writer’s Workbook.

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