DEFINITION:

　

The comma is a mark that helps readers keep sentence parts separate from each other but related to each other so that the meaning of one part is clearly different from the meaning of the other.

　

For example:

If you drive Fred will read the map.

　

But when you add a comma, the meaning of each part and the relationship between them becomes clear:

　

If you drive, Fred will read the map.

　

  1. Use a comma to separate independent clauses when they are joined by the coordinating conjunctions: for, and, nor, but, or, yet, so. (fanboys)

    2. For example:

    You should call Hank tonight, for he is all alone.

    　

  2. Use a comma to separate words, phrases, and clauses written as a series of three or more coordinate elements.

    3. For example:

    The audience was seated, the lights were dimmed, and the curtain was raised.

    　

  3. Use a comma to separate two or more coordinated adjectives that modify the same noun.

    4. For example:

    An expensive, well-tailored suit is hung on the wall.

    　

  4. Use a comma to separate sharply contrasted coordinate elements.

For example:

He was merely quiet, not weak-minded.

　

5. Use commas to set off all nonessential modifiers. Do not set off essential modifiers.

For example:

Mary, who is flying to USA next week, is my friend. (nonessential)

　

6. Use a comma after an introductory adverbial clause, verbal phrase, or absolute phrase.

For example:

The bus having stopped, the tourists filed out. (absolute phrase)

7. Use commas to set off nonessential appositives.

For example:

Tennyson and Browning, two Victorian poets, were outstanding literary spokesmen of their day.

　  8. Use commas to set off items in dates, geographical names, and addresses and to set off titles after names.

For example:

April 2, 1999, was his marriage memorialize day.

　

9. Use commas to set off words used in direct address.

For example:

I think, my friend, that I can do it.

　

10. Use a comma after a mild interjection and after yes and no.

For example:

Oh, how funny you are.             

　

11. Use a comma to separate an independent clause from a question dependent on the clause.

For example:

He will go to the place, won’t he?

　

12. Use commas to set off expressions like he said or she replied when they interrupt a sentence of direct quotation.

For example:

“He is sick,” she replied, “he will not come.”

　

13. Use commas to set off certain parenthetical elements.

For example:

I was, however, too hungry to eat the food.

14. Use a comma to prevent the misreading of a sentence.

For example:

To Mark, the teacher had made a study plan.

　

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