1. Commas control meaning. Learn the comma rules; control meaning.

2. COMMA RULE ONE Set off the year from the month and day in a date.
Examples:
On November 5, 1997, the American voters
go to the polls.
Judy signed the contract on July 26, 1992,
a day she will always remember.
NOTE: Always place a comma AFTER the year as well as before it.

3. COMMA RULE TWO
Separate a state’s name from that of the city with a comma.
Note: Always place a comma AFTER the state’s name as well as before it.
Examples:
Jose hailed from Topeka, Kansas, not from Mexico as many of his friends thought!
Boston, Massachusetts, is more famous for its cheesecake that for its beans.

4. COMMA RULE THREE Set off three or more items in a list.
Note: Always place a comma BEFORE the coordinator (and, but, or).
Examples:
John, Sara, and Bill came.
Trini cycled, swam, and ran.

5. COMMA RULE FOUR Set off the salutation of a letter. Examples:
My dear Mr.. Smith,
Members of the committee,
Note: Capitalize only the first word and any proper nouns in a salutation.

6. COMMA RULE FIVE Set off the closing of a letter. Examples:
Very truly yours,
As ever, your friend,
NOTE: Capitalize only the first word of a closing.

7. COMMA RULE SIX Set off direct address. Examples:
I think, Mary, that we should head home.
We’re sorry, Mr.. Gomez.
NOTE:
Leaving out the commas can have unexpected effect:
I’m sorry Mr. Gomez.
(I wouldn’t say that about myself. Would you?)

8. COMMA RULE SEVEN
Set off any introductory word or phrase, no matter how short.
Examples:
After school, Mitzy performs in public.
Happily, the annoying noise ended.
In 1492, Columbus sailed the ocean blue.

9. COMMA RULE EIGHT
NOTE: An appositive is a word or phrase which offers information which is interesting but NOT necessary. It is NON-RESTRICTIVE (We do not need to hear about the cats to learn that Sophie bought a new vehicle!)
Set off an appositive, a word or phrase which renames or clarifies a noun.
Example:
Sophie, the lady with ten cats, bought a new truck.

10. COMMA RULE NINE
Set off words or phrases which interrupt the flow of the sentence.
Example:
The truth, however, was hard to discover.
Otis decided, in fact, to leave school.
NOTE: Avoid placing a sentence within a sentence.
Wrong: The tax papers were, I think, mailed on April 12.
Right: I think that the tax papers were mailed April 12.

11. COMMA RULE TEN
Set off non-restrictive elements, clauses and phrases which offer information which is interesting but not necessary to the meaning of the sentence (an appositive is a special form of non-restrictive element; see Comma Rule Eight).
Example: The manager, who has six children, changed the work schedule.

12. COMMA RULE ELEVEN Set off ALL introductory, subordinate clauses.
Examples: When the storm hit, the power failed.
Although he felt ill, he took the test.
NOTES:
1. every clause has a verb.
2. every subordinate clause has a subordination conjunction or relative pronoun which prevents it from being a whole thought (sentence) on its own.

13. COMMA RULE TWELVE
Cojoin sentences with a comma and one of the coordinators (FANBOYS).
Examples:
Anna ate, for she was hungry.
Harry will sing, and he will dance.
Sonny needs no help, nor will he ask for any.
Hank has the paint to finish, but he has no time
Enos will carry the lead banner, or he will film the event.
Most of the group received invitations, yet few will come.
Everyone wanted the principal to resign, so she did.