On the Use of Commas
1. Put a comma before and, but, for, or, nor, yet, or so when they connect two
independent clauses.
¾ I may try to get a new job, or I may stick with this one.
Each of the phrases, “I may try to get a new job” and “I may stick with this one,”
are independent clauses; they can be written as sentences: I may try to get a new
job. I may stick with this one. Be sure that such words DO connect two
independent clauses. The following sentence is merely one independent clause
with one subject and two verbs. Therefore, no comma should be used.
¾ She wanted to go to college but didn’t have enough money.
Notice that the phrase, “She wanted to go to college” is an independent clause
and can be written as a complete sentence: She wanted to go to college. BUT the
phrase, “didn’t have enough money” is a dependent clause; it cannot be written
as a complete sentence because it has no subject. It is dependent upon the other
clause for its subject, “She.”
2. Put a comma between items in a series.
¾ He ordered pie, cake, and ice cream.
It’s permissible to omit the comma before the “and” connecting the last two
members of a series, but more often a comma is used.
¾ He wore a baggy old red sweater. The bright blue morning sky lifted her.
Some words “go together” and don’t need a comma between them even though
they do make up a series.
3. Put a comma after an introductory expression or after a thought that
doesn’t flow smoothly into the sentence. It may be a word, a group of
words, or a dependent clause.
¾ Yes, I’ll go. Well, that was the end of that. It’s cold this morning, isn’t it?
When a dependent clause comes at the beginning of a sentence, put a comma after
it. Dependent clauses do not need commas when they come at the end of a
sentence. For example, compare the following:
¾ Before he arrives, we should all hide. We should all hide before he arrives. Look for a dependent clause when the sentence contains:
After
Although
As
As if
Because
Even if
Even
Though
Ever since
How
If
Since
So that
Than
That
Though
Until
What
Whatever
When
Whenever
Where
Whereas
Wherever
Whether
Which
Whichever
While
Whom
Whose
Why
¾ Although he ate dinner, he was still hungry. Wherever they went, they were
accepted as friends.
Even though these above listed words are often used in dependent clauses, they
can often appear in sentences without dependent clauses. For example:
¾ Wherever did you get that hat?
4. Put commas around the name of a person spoken to.
¾ I think, Melissa, that we’re late. Chris, how about a game of chess? Are you
ready, Amy?
5. Put commas around an expression that interrupts the flow of the sentence.
(Such as however, moreover, finally, therefore, of course, by the way, on
the other hand, I am sure, I think).
¾ He did go to class. He did, however, go to class. He arrived home. Finally, he
arrived home. It was her paper. It was his paper, I think.
6. Put commas around nonessential material. Nonessential material consists
of words that are not necessary for the sentence to make sense.
¾ Mariam Tilden will speak tonight. Mariam Tilden, who heads the hospital
volunteers, will speak tonight. The new machine is much faster. The new
machine, which was ordered by the supervisor, is much faster.