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Students often place commas
throughout their papers as if they are sprinkling raisins
on their oatmeal. Although you shouldn’t use a comma
unless you know a rule for it, commas are necessary for others
to understand what we have said, to “get it.” It
is easy to know when someone has finished a sentence: we
see a period there. It is not as easy to know where a writer’s
thoughts are going inside a sentence. Commas cause the reader
to pause and better understand the elements that make up
the sentence. In this module you will learn how to
use commas correctly. Lessons will cover rules for
comma use and common comma mistakes.
Quick Comma Rules...
In most situations, five general rules for comma use will
help students use commas correctly. Some special situations
for comma use are discussed toward the end of this module.
- use a comma to separate items in a series.
- use a comma with a coordinating conjunction to
separate two independent clauses
- use a comma to set-off non-essential
elements such as a phrase or clause. Commas should
be placed before and after a non-essential element in the
middle of a sentence
- use a comma after an opening clause, word,
- use a comma to follow conventions of
naming, citing sources, presenting addresses, dates, etc.
Rule 1: separate items in a series
Separating items in a series signals to the reader
that the items are "like" in some respect.
The series may be a series of adjectives describing
something, a series of things to pick up at the market,
or a series of adjective, infinitive, or prepositional
phrases. A series of two or more items should
be separated by commas; however, there is some debate
about whether the last item in a list of three items
should take a comma. Many grammarians would argue
in this situation, leaving out the last comma is acceptable. However, MLA
format rules do require a comma before the last
item in a series of three or more elements.
Felix dislikes spinach, broccoli, green beans,
and brussels sprouts—any vegetable
Doing the dishes, washing the clothes, and mopping
the floor are the chores I hate most.
Finding healthy, appetizing fast food is
Note: Sometimes a series seems to be "like" when
it is not. In this situation, a comma should
not be used between the items. For example,
She left her beautiful black leather handbag
on the bus.
Haunted by the memory of last year's painful
knee surgery, she protected her knee with
a strong brace during the tennis match.
A useful way to tell if items are "like" is
to try placing the word "and" between every
item; if the sentence makes sense, then the items are
like; if not, then they are unlike items and should
not be separated by commas.
Rule 2: use a comma to
separate two independent clauses
Two or more independent clauses joined together
need strong punctuation: a semi-colon, or a comma and
a coordinating conjunction. This punctuation
tells the reader that the clause could
stand on its own as a complete sentence. Writers join
clauses together to show a close relationship between
ideas and to vary the rhythm in the sound of their
sentences. And the coordinating conjunctions—and,
nor, for, but, yet, and so—also help writers identify
the relationship between ideas and create coherence
in their writing (take a look at the module on coordination
and subordination for more information about using
conjunctions effectively). Without adequate punctuation,
the sentence will be a "run-on sentence": if
no punctuation is included between independent clauses,
the error is a "fused sentence," if the coordinating
conjunction is provided and the comma is omitted, the
error is a "comma splice" (for more detail, explore
the module on run-on
Felix does not like spinach, nor does
he like broccoli.
We will be going to the mountains again this summer,
but this time we will bring mosquito repellant.
After graduation, Maya is going to travel throughout
Southeast Asia for a year, and I will be staying
home flipping burgers and going to school.
Rule 3: use a comma to set off
A non-essential element is information that is added
to the core of a sentence to add further information—information
that is useful, but not really essential to understanding
the basic assertion. To signal the reader that
a word, phrase, or dependent clause is non-essential
information, writers set these elements off by commas
before and after the addition. The information
is thus enclosed by commas. If the phrase occurs at
the beginning or end of the sentence, only the comma
separating the phrase from the rest of the sentence
She is, as you can probably
tell, pretty nervous
about public speaking.
As you can probably tell, she is pretty
nervous about public speaking.
Once upon a time, before
television, before computers, people read books
Jake brought his best friends from school,
John and Alex, home with him for Thanksgiving
Note: In the last example above, the names of Jake's
friends are non-essential information: Jake has only
two best friends. However, if the names are essential
to identifying the person, the names should not be
set off from the sentence. Consider how the meaning
changes with the presence or absence of enclosing commas
in the following sentences:
My sister Maria is pretty fun to hang out with.
My sister, Maria, is pretty fun to hang out with.
In the first
sentence, because the name of the sister is included
as necessary to the meaning of the sentence, the speaker
could have more than one sister—this particular
sister is fun to hang out with. In
the second sentence, because the name of the sister
is non-essential information, the speaker must have
only one sister—my sister, whose name, by the way,
is Maria, is fun to hang out with.
Rule 4: use a comma after an opening clause, word,
Introductory Clauses: When
beginning a sentence with an introductory clause (as
in this sentence), a comma is typically necessary to
signal the reader as to when the introductory phrase
or clause is complete.
As you can see, the problem is much bigger
than we imagined.
Because we have had so much
rain this year, construction
of the new highschool will take an additional six
Jake brought his best friends from school, John
and Alex, home with him for Thanksgiving dinner.
Watch out, however, for clauses used
as the subject of a sentence; one should never separate
a subject from the verb of the sentence:
What she has always wanted is now within her reach.
Referring to what others have
said shows that you
are participating in an ongoing conversation about
Introductory words: Sometimes
a sentence begins with a single word that needs to
be set off from the rest of the sentence.
exclamations or interjections:
Hey, I thought you were going to study tonight instead
of come with us to the movies.
Ok, then show me how you do it.
No, I don't want pineapple on my pizza.
a name in a direct address:
Miguel, do you want another cup of coffee?
a sentence adverb: these are special transition
words that always take a comma, or if they occur in
the middle of a sentence, they are enclosed by commas. Examples
of sentence adverbs include moreover, however,
nevertheless, furthermore, frankly, sadly, and mercifully. Never
use a sentence adverb to connect two independent clauses
unless you use a semi-colon before the sentence adverb.
I would love a new plasma television; however, I cannot
Sadly, she has the flu and will have to skip the concert.
Note: Grammarians disagree about the word "hopefully"
used as a sentence adverb. Most hate this construction,
arguing that it is ambiguous—the writer could mean
a hopeful prediction, or "I am hoping."
Introductory phrases add
information to the sentence and create interest in
and anticipation for the information to follow. All
phrases should be set off from
the rest of the sentence by a comma with two exceptions:
short prepositional phrases do not need a comma unless
it is necessary for clarity, and introductory
appositive phrases that are essential to the sentence
should never be separated from the subject by a comma.
To help him understand how
an internal combustion engine works, I drew
In San Francisco one finds plenty of good restaurants.
At the restaurant we all ordered burgers
Without a doubt, she is the nicest person I have
The acclaimed critic Roger Ebert has been ill recently,
and unable to host his television program, Ebert
Rule 5: use a comma to follow conventions
What follows reads a bit like a laundry list
of comma use rules, but unfortunately or fortunately
(depending on how we look at it), many conventions
for the presentation of dates, names, times, citations,
and quotations have risen up over time. Troublesome
they may be, but these conventions allow us to quickly
share and process information.
. . . Use a comma to
separate a city from a state, and after the state before
continuing with the rest of the sentence:
I have lived in San Francisco, California,
for most of my life.
. . . Use a comma to separate the
day of the month from the year, and after the year
before continuing with the sentence:
The twins were born in June, 1979, one month before
my 30th birthday.
. . . Use commas to surround titles or degrees:
Professor Pete McSeed, Ph.D., received his doctoral
from Amherst College a year before taking a teaching
job at Yale.
. . . Commas used with quotations are a bit tricky. When
introducing a quote with a short introductory phrase
like "He said," "Twain argues," or "As
Huck puts it,"
the phrase should be set off from the
quote by a comma. However, after an independent
clause, a colon should be used instead.
In The Adventures of Huckleberry Finn, Huck
says, "All I say is, kings is kings, and
you got to make allowances. Take them all around, they're
a mighty ornery lot. It's the way they're raised."
Huck embraces life in the wild to the extent that
a raft moving down a river can provide all the
home he really needs: "We said there warn't no home
like a raft, after all. Other places do seem so cramped
up and smothery, but a raft don't. You feel mighty
free and easy and comfortable on a raft."
It is also important to note that a comma used after
a quote to separate it from the rest of the sentence
goes inside the closing quote.
Twain's short story "Hunting the Deceitful Turkey,"
is wildly funny.
. . . Use a comma to emphasize a shift or to cause
the reader to pause before an important contrast or
point of emphasis.
He was angry, furious even.
Tears were streaming down her face because she was
happy, not sad.
You are going to make the cake for the party, aren't
When Not to Use a Comma
Here are some quick "don'ts" that may help you break any
bad habits with comma use.
Don't use a comma to separate the subject from the verb.
wrong: To err, is human.
corrected: To err is human.
Don't place a comma between two
sentence verbs or verb phrases.
wrong: She walked out of the room,
and started screaming about the grade on her essay.
corrected: She walked out of the
room and started screaming about the grade on her
Don't place a comma between
two nouns, noun phrases, or noun clauses in a compound subject
or compound object.
wrong: I told my boss that I was sick,
and that I would not be coming to work.
corrected: I told my boss that I was
sick and that I would not be coming to work.
Don't put a comma after the main clause when a
dependent clause follows it.
wrong: I am not going to work today,
because I am sick.
corrected: I am not going to work today
because I am sick.
Don't sprinkle commas throughout your
writing to try and imitate a speaking voice. Rely instead
on language and logic, and an occasional well-placed comma
to create voice. Take
a look at a parody of this kind of comma abuse by blogger
I, love, the comma, hate, comma abuse, hate, the people,
who hate comma abuse, and hate, the people, who, love comma
abuse, the perpetrators, the people, who, love them, the
people, who, hate, them, and the, fandoms, which spawn them.
Also? Everyone else.
Quick comma rules
1. Use a comma
in a series
2. Use a comma
to separate independent clauses
3. Use a comma
to set-off non-essential elements
4. Use a comma
after an opening clause, word, or phrase
5. Use a comma
to follow conventions
6. When not to
use a comma