We use commas to mark off parts of a sentence in order to make our writing clearer. We use them to separate items or to enclose items.
COMMAS TO SEPARATE
1. Before the coordinating conjunctions and, but, for, yet
I placed the typed sheet on the table, and he picked it up and read it slowly. His face turned red, but
2. When listing three or more items in a series, including the last item before and
The house was empty, cold, and dark. (three adjectives)
She bought pears, apples, oranges, and bananas. (four nouns)
She rushed into the house, up the stairs, and into her room. (phrases)
Larry fetched the water, Mort built the fire, and I opened the cans. (clauses)
3. Between coordinate (equal) adjectives preceding a noun
The open doorway of the gray frame house revealed a dirty, dark, smelly hallway.
(You could not place and between gray and frame and thus need no comma.)
4. After many introductory elements, especially if they are long
To get a better view of the stage, I chose a seat on the aisle.
Having climbed the steep trail, he proceeded to set up his camera.
No, we are not in danger.
Well, what are we going to do now?
5. Between any two words that might be mistakenly read together
Once inside, the dog scampered all over the furniture. (not once inside the dog
While we were eating, the table collapsed. (not while we were eating the table
COMMAS TO ENCLOSE
We use commas to enclose words, phrases, or clauses that break into the normal word order of a sentence. These "interrupters" are framed by two commas (unless, of course, they come at the beginning or the end of the sentence).
1. Nonessential(nonrestrictive) adjective clauses or phrases
If the word being modified is already completely identified, the clause or phrase is nonessential to the sentence's meaning and requires commas because it interrupts.
Mr.Hacker, who teaches our class, is an ex-Marine. (identified by name)
My mother, who is an ardent Democrat, refused to admit defeat. (only one mother)
The man who delivers our mail is a neighbor of ours. (Who delivers our mail
2. Most appositives
An appositive is a phrase or clause that immediately follows a noun and modifies it.
Mr. Miller, our biology teacher, told me about the competition.
The new boy, the one with red hair, likes me.
However, in this sentence, a comma is not necessary:
The poet Wordsworth was a leading figure of the early nineteenth century.
3. Absolute phrases
The cat being away, the mice will play.
4. Parenthetical expressions
His appearance, I must say, was not impressive.
You will find, for example, that the format is not attractive.
5. Words used in direct address
I can tell you, Henry, that we are all proud of you.
"Carol, your essay must be rewritten," said her teacher.
6. Expressions designating the speaker in direct quotations
''With your permission," he replied, "I will do it immediately."
(Other marks than commas may be used if the sentence justifies their use. Only use one punctuation mark.)
(question mark after question--doesn't need a comma)
7. In dates and addresses
On July 14, 1904, in a little cottage at 316 High Street, Mayville, Illinois, the wedding took place.