WHAT IS A COMMA?
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A comma is a punctuation mark that separates words, ideas or phrases within a
sentence. It is also used to indicate a pause, or caesura, in a sentence.
WHAT ARE THE FUNCTIONS OF A COMMA?
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There are many functions of a comma, but there are six important usages that
every writer should know and follow. These six functions are listed below.
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An independent clause is a group of words that contains both a subject and a predi-
cate and can stand alone as a complete sentence. Use a comma before and, but, for,
or, nor, yet, and so when they are used to connect two independent clauses.
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A dependent clause is one that cannot stand alone as a complete sentence and when
used in the beginning of a sentence is set apart from the rest of the sentence using a
comma. This constitutes an introductory element. Below are examples of comma
usage with introductory elements.
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Remember: Make sure that the sentence is in fact made up of two independ-
ent clauses. The following sentence does not need a comma because it is
made up of only one independent clause with one subject and two verbs.
Emma needed to get to work but didn’t have a ride.
Transitional Words and Phrases:
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Use a comma after a transitional word or phrase (such as however, moreo-
ver, finally, therefore, of course, by the way, on the other hand) when it is
used in the beginning of a sentence.
I would love to attend your party
I have a previous engagement.
, but
I would love to go.
Yes,
I don’t know if that is a good idea.
Well,
Verbal and Prepositional Phrases:
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Use a comma after a phrase that begins with a preposition, a participle, or an infinitive
in a sentence.
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Use a comma to separate three or more words or phrases in a series.
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A clause may be essential or nonessential depending upon its relationship to the
meaning of the sentence. Nonessential clauses may be interesting to add, but the
sentence would still be clear without it. Use commas around nonessential clauses in a
sentence. Note: If an essential or nonessential clause is describing a noun or pronoun
in a sentence, it is called an appositive clause.
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Note: Do not use a comma to set off a dependent clause at the end of a sentence.
Mike’s favorite sports are football, soccer, and tennis.
She woke up early, ate breakfast, took a shower, and was on her way.
Specifying that Professor McEwan is the Director of the Writing Center
does not change the meaning of the sentence. Therefore, the Director of the
Writing Center is a nonessential clause and is separated with commas.
However, in this example, the clause “who is the Director of the Writing
Center” is an essential clause because it identifies the woman being referred to in
the sentence. Therefore, this clause does not need commas around it.
During the semester,
I always have several papers to write.
she kindly declined the invitation. Knowing that she didn’t have time to go,
the girl finally told the truth. To avoid punishment,
after you have eaten. You can do the dishes
Mom always hangs her key by the door when she gets home.
the Director of the Writing Center, Professor McEwan, works Monday through Friday.
The woman who is the Director of the Writing Center works Monday through Friday.
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Everyday material can be defined as dates, addresses and locations, and professional
titles. Each has its own set of rules in regards to comma placement in a sentence.
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Use commas to set off a direct quotation in a sentence. A comma can be placed be-
fore or after the quote but is always placed in accordance with the identifying tag.
The identifying tag is the phrase that identifies the speaker in the sentence (i.e. she
said). Note: The comma always lies within the closing quotation marks.
“I have always wanted to be a doctor,” my sister announced.
“Hang up your towel after your shower,” my mom instructed my brother, “or
else it won’t dry properly.”
Professor Smith said to the class, “Please be on time for all classes and bring all
necessary materials.”
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Remember: When the identifying tag comes between two completely quoted sentenc-
es, a period follows the identifying tag.
“I wonder how long they have known each other,” Maria pondered. “It seems as
if they get along so well.”
“Do you think we’ll have enough time?” Maria asked. “We’re running pretty
late.”
Dates:
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Use a comma after the date and the year in a sentence.
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Remember: When using only the month and the year in a sentence, no comma is
needed.
December 2006 was the warmest December on record in New Jersey since tem-
peratures were first recorded in 1895.
in a small town in New Jersey. August 17, 1983, Paul was born on
at 6’oclock in the evening. June 16, 2007, Annie’s graduation party will be held on
Addresses and Locations:
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When a location has two or more parts to it, a comma is needed after each part in
the sentence.
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Remember: If the two locations are joined using a preposition or if only one location
is listed, no comma is needed.
Pennsylvania is my favorite state because of all the open spaces.
The weather in Albany in New York is very different from the weather in Al-
bany in California.
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A comma is needed to separate parts of an address when two or more parts are used.
Write to Angela Beaver at 546 West Front Street, Burtonsville, Maryland 20866.
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Remember: If an address is written out line by line, no comma is needed after the
street address.
Angela Beaver
546 West Front Street
Burtonsville, MD 20866
Professional Titles:
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A comma is needed to set off a professional title in a sentence.
Fran has always wanted to travel to Florence, Italy, but she has never had the chance.
Glen Bradford, M.D., will be speaking at a conference at the end of this month.
Last modified 8/11/11
