The comma is the most abused punctuation mark. Writers are sometimes so worried about following rules that they forget to pay attention to the way the words sound when spoken. Commas help a reader understand the rhythm of the sentence. If you are having comma problems, say your sentence out loud and listen for natural pauses. The function of a comma is to make the reader pause. The omission of a comma can cause phrases and clauses to crash into one another, thereby confusing the reader.
Commas can influence the meaning of your sentence. Consider the following:
The food tastes terrible, however the cook fixes it.
The food tastes terrible, however, the cook fixes it.
In the first sentence, the food tastes terrible no matter how the cook fixes it. In the second sentence, the food is bad but the cook improves the taste. Again, the comma controls the meaning.
RULES FOR COMMAS
1. Use a comma to separate two independent clauses connected by and, but, or, nor, for.
Bob was usually a quiet man, but he screamed upon entering the room.
The strange man lying under the table appeared to be dead, or just possibly he was only napping.
If the independent clauses are short, you may omit the comma.
The man was still and his foot was bleeding.
His hat was on but his pants were off.
2. Use a comma to separate elements in a list or series.
Bob tried to breathe, to keep from fainting, and to remember his first aid.
Next to the man were a bassoon, a water balloon, and a raccoon.
3. Use a comma to separate introductory phrases and clauses from an independent clause that follows, particularly if the phrase or clause is long.
After catching his breath, Bob squatted next to the man and took his pulse.
When he felt nothing, Bob picked up the bassoon and blew.
Although he had never played a bassoon before, he somehow managed to make beautiful music.
Again, if the introductory phrase is short, you may omit the comma:
When he stopped playing it was dark outside.
4. If the introductory phrase is a gerund, participial, or infinitive phrase, use a comma even if the phrase is short. Otherwise, the reader may be confused:
When Bob began to eat, rats ran across the carpet.
NOT: When Bob began to eat rats ran across the carpet.
5. In a series of adjectives, use a comma if the adjectives could also be separated by and.
The nimble, fat, and furry raccoon began to poke at the water balloon.
(Could be written as: The nimble and fat and furry raccoon…)
If the and doesn’t fit, leave out the comma:
The man’s white cotton shirt was balled up in a corner.
(Would not write as: The man’s white and cotton shirt . .)
If this rule seems confusing, read the sentence aloud. If you make a slight pause between adjectives, put in commas. Otherwise, leave them out. Another test: if you can change the order of the adjectives, insert commas. For example:
The handsome, brilliant scholar
Or: The brilliant, handsome scholar
The frilly party dress
Not: The party frilly dress
6. Use commas to set off clauses, but do not use commas for restrictive clauses. An essential or restrictive clause is one that can’t be left out of a sentence. Clauses that don’t define can be lifted from the sentence without changing the meaning. Look at these sentences:
Bananas that are green taste tart.
That are green defines which bananas we mean. We cannot remove it.
Bananas, which grow in the tropics, do not need refrigeration.
Which grow in the tropics refers to all bananas. The clause can be lifted from the sentence without changing the meaning.
Let’s look at a sentence that you could punctuate either way, depending on the meaning:
The men who were tired and hungry began eating sardines.
who were tired and hungry is a defining clause, telling us which men we mean.
The men, who were tired and hungry, began eating sardines.
who were tired and hungry describes all of the men and doesn’t differentiate these men from other men who weren’t tired and hungry.
7. Commas should set off words or phrases that interrupt the sentence.
Now then, let’s get down to work.
“Save me,” he said, before falling down the stairs.
On the other hand, error can lead to revelation.
What the candidate promised, in fact, is impossible to achieve.
Hello, I must be going.
8. Use commas to set off an appositive. An appositive is a noun or pronoun that explains or identifies the noun that precedes it.
Mrs. Daniels, my favorite teacher, is wearing a wig.
Ralphie, the president of the student council, is on probation.
9. Commas go inside quotation marks, never outside:
“I do like the taste of chocolate,” she said, “but I am allergic.”
Using commas correctly is one way to make your writing clear. Reading your sentences aloud is a good way to find the natural place for commas, as is inspecting your sentences for ambiguity or confusion.