Students often sprinkle commas through their papers as if they were shaking salt out of a salt shaker. Rule of thumb: Don’t use a comma unless you know a rule for it. Commas are important because without them, a reader would often have to reread a sentence to find out what the writer meant.
While the use of commas also requires sensitivity to the rhythm and pace of a line and to the sense of what is being said, even master chefs started their careers by first following a recipe. So MASTER THESE SIX RULES, and your writing will be easier to read:
- Put a comma before for, and, nor, but , or yet, and so (FANBOYS) when they connect two complete sentences (independent clauses).
- -We lost our oars, and that was the end of our boating.
- -We may leave Friday, or we may wait until Monday.
Be sure such words do connect two complete sentences and not two words or two phrases. The following sentence is merely one sentence with two verbs.
- -I wanted to got but couldn’t get my car started.
- Put a comma between items in a series.
- -Hurrah for the red, white, and blue.
- -She put down the phone, picked up her keys, and left.
Some words “go together” and don’t need a comma between them even though they do make up a series.
- -The dear old lady.
To tell whether a comma is needed between two words in a series, see whether “and” could be substituted naturally between them. It would sound all right to say red and white and blue; therefore, commas are used. But it would not sound right to say dear and little and old lady; therefore, no commas are used.
Sometimes, journalists will omit the comma before the and connecting the last two members of a series, but it should always be used in college writing. Consider the following letter a reader wrote to Time in response to that magazine’s policy of omitting the final comma before the conjunction:
“This omission reminds me of my fifth-grade teacher’s lesson on the subject. A father’s will stipulated that his estate be shared equally between his three sons: ‘Tom, Dick and Harry.’ Tom took the matter to the grammar court and won the case; he inherited half the estate, and Dick and Harry split the other half.”
- Put a comma after an introductory expression that doesn’t flow smoothly into the sentence or before an afterthought that is tacked on. It may be a word, group of words, or a dependent clause.
- -Yes, I’d like to go swimming.
- -Below, the submarine checked the water for mines.
- -Moreover, the umpire agreed with me.
- -Keeping a steady gait, the old horse won the race.
- -When I entered, the courtroom was packed.
- -It’s too late to register now, isn’t it?
Notice how in the second and fifth sentences above, the comma is necessary. Otherwise the reader would read Below the submarine... and When I entered the courtroom...before realizing that this was not what the writer meant. A comma prevents misleading.
- Put commas around the name of a person spoken to.
- -I think, Dawn, that you are absolutely right.
- -Ephraim, how about a game of tennis?
- -I’ve finished waxing your surfboard, Brice.
- Put commas around an expression that interrupts the flow of a sentence. Such an expression cold be however, moreover, therefore, finally, of course, by the way, on the other had, I think.
- -We knew, of course, that we were going to be late.
- -We didn’t expect, therefore, to get good seats.
- -She should, I think, take a vacation.
But remember that when an interrupting word comes between two complete sentences, the word always has a semicolon before it and, usually, a comma after it.
- -I overslept; however, I still arrived at the interview on time.
- -I didn’t study in high school; now I do.
Thus a transitional word however or therefore may be used in three ways:
- -as an interrupter (commas around it)
- -as a word that flows into the sentence (no commas needed)
- -as a connecting world between two independent clauses (semicolon before it an often a comma after it.
- Put commas around nonessential material.
- -Dorothea Fox, who is running for mayor, will speak tonight.
- -The woman who is running for mayor will speak tonight.