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The Use of Commas in Written English

written by: Heather Marie Kosur • edited by: Rebecca Scudder • updated: 11/28/2013

Punctuation marks help readers to more easily read and understand writing. This article explains and provides examples of the ten basic uses of commas in the English language. Also included is a downloadable reference sheet.

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    Commas

    Like all punctuation marks, commas ensure the clarity of writing by organizing similar elements and representing intonation present in spoken language. Commas perform ten basic functions.

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    Separate words in a series

    English 1. Use commas to separate items in a series. Place a comma after each item in the series except for the last item. Place the last comma before the coordinating conjunction. For example:

    • Dogs, cats, mice, and squirrels are mammals.
    • Farmers grow yellow corn, orange pumpkins, green peppers, and purple grapes.
    • The movie is long, dull, and overrated.
    • Performers sing, dance, or act.

    Do not use commas to separate subjects or objects with only two nouns or noun phrases. Do not use commas to separate predicate adjectives with only two adjectives or adjective phrases. Do not use commas to separate predicates with only two verbs or verb phrases. (The asterisk * marks incorrect usage.) For example:

    • *Doctors, and veterinarians have medical degrees.
    • *Cats like mice, and fish.
    • *Snow is cold, and wet.
    • *Athletes run, and jump.
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    Separate independent clauses joined by coordinating conjunctions

    2. Use commas to separate two or more independent clauses joined by coordinating conjunctions. The coordinating conjunctions are and, but, for, nor, or, so, and yet. Independent clauses contain both a subject and a verb that function as a complete sentence. For example:

    • The baby ate his formula, and the toddler drank her milk.
    • My brother wanted pumpkin pie, but my sister wanted chocolate cake.
    • The student was confused, so the teacher offered extra help.
    • I came, I saw, and I conquered.
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    Between coordinate adjectives

    3. Use commas between coordinate adjectives. Coordinate adjectives directly and equally modify or describe the same noun. The word order of coordinate adjectives can be changed without changing the meaning. For example:

    • The restaurant served plain, tasteless soup. (plain and tasteless both describe the soup)
    • The mean, malicious child kicked the puppy. (mean and malicious both describe the child)

    Do not use commas to separate cumulative adjectives. The meaning of cumulative adjectives is dependent on the order of the adjectives. For example:

    • The big blue house is on the corner. (big describes the blue house)
    • The pretty calico cat likes to cuddle. (pretty describes the calico cat)
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    Separate nonrestrictive modifiers

    4. Use commas to separate nonrestrictive modifiers. Nonrestrictive modifiers are optional, meaning such modifiers can be added or deleted without changing the meaning of the main clause. For example:

    • The book, which I left in my car, is from the library.
    • The puppy, with the blue leash, belongs to me.

    Do not use commas to separate restrictive modifiers. Restrictive modifiers are essential to the meaning of the main clause. For example:

    • The book that I left in my car is from the library.
    • The puppy with the blue leash belongs to me.

    Nonrestrictive modifiers are distinguished from restrictive modifiers by the context of the sentence. The difference between the modifier with the blue leash in the first example and the second example is that the puppy in the second example can only be identified by the fact that he is wearing a blue leash, making the modifier necessary and restrictive. The inclusion of the modifier with the blue leash in the first example, however, is optional, additional information, and, therefore, nonrestrictive.

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    Separate appositives that are not essential to the meaning of the sentence

    5. Use commas to separate appositives that are not essential to the meaning of the sentence. Appositives are nouns, pronouns, or noun phrases that modify or explain another noun, pronoun, or noun phrase. For example:

    • John Lennon, the musician, was killed by a fan.
    • An aspiring actress, my cousin always auditions for lead roles.

    Do not use commas with an appositive essential to the meaning of the sentence. For example:

    • My dog Espen is a shih tzu.
    • The singer Stevie Nicks was a member of Fleetwood Mac.
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    Separate adverbs and short parentheticals that are not essential to the meaning of the sentence

    6. Use commas to separate adverbs and short parentheticals that are not essential to the meaning of the sentence. For example,

    • Classes, however, were canceled because of the storm.
    • Then, the power went out.
    • Mice and rats, for example, eat corn and other grains.
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    After prepositional phrases and clauses that precede the main clause

    7. Use commas after prepositional phrases and clauses that precede the main clause. Phrases that precede the main clause include prepositional phrases functioning as adjuncts and adverbials and participle phrases functioning as modifiers. Clauses that precede the main clause include subordinate clauses functioning as adverbial clauses. For example:

    • After the movie, the friends decided to get dinner. (phrase)
    • Digging in the beach, the child found a seashell. (phrase)
    • Shaken in the car ride, the bottle of soda exploded. (phrase)
    • After the friends saw the movie, they decided to get dinner. (clause)

    Do not use commas before prepositional phrases and clauses that follow the main clause. For example:

    • The friends decided to get dinner after the movie. (phrase)
    • The friends decided to get dinner after they saw the movie. (clause)
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    Separate alternative or contrasted coordinate phrases

    8. Use commas to separate alternative or contrasted coordinate phrases. For example:

    • The woman is an ignorant fool, not a stupid moron.
    • Judas, not Peter, kissed Jesus.
    • Impatient, maybe resentful, patients destroyed the magazines.
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    Transition between quotations

    9. Use commas to transition between quotations. For example:

    • Martin Luther King, Jr. said, "I have a dream."
    • "Four score and seven years ago," began Abraham Lincoln.

    Do not use commas to transition from quotations that end with exclamation or question marks. For example:

    • "Who wants to present first?" asked the teacher.
    • "I want some candy!" the little girl screamed.
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    In dates, geographical places, numbers, personal titles, direct addresses, and brief interjections

    10. Use commas in dates, geographical places, numbers, personal titles, direct addresses, and brief interjections. Use commas to separate the day of the week from the month, the day from the year, and the year from the rest of the sentence. For example:

    • Abraham Lincoln was born on Sunday, February 12, 1809, in a log cabin.
    • On January 14, 2008, I became a writer.

    Do not use commas when the day precedes the month. Do not use commas between months and years or seasons and years. For example;

    • Abraham Lincoln was born on Sunday 12 February 1809 in a log cabin.
    • The storms of December 2008 stranded many travelers.
    • Many babies were born in spring 1985.

    Use commas between street addresses and city names, city names and state names, and state names and countries. For example:

    • The library is located at 201 North School Street, Normal, Illinois.
    • Many students are from Chicago, Illinois.
    • Eva Peron is from Buenos Aires, Argentina.

    Use commas to mark off thousands, millions, billions, and so on. For example:

    • The car costs $10,000.
    • A fire destroyed 123,456,789 pieces of art.

    Do not use commas in street address or page numbers. For example:

    • The family lives at 7531 Oak Street.
    • Please turn to page 8462.

    Use commas to separate personal titles from names. For example:

    • Gregory House, M.D., is a medical genius.
    • Martin Luther King, Jr. fought for equal rights.
    • Jane Doe, Associate Dean of Technical Services, hired the new employee.

    Uses commas to separate direct addresses. For example:

    • Please clean the kitchen, Oliver.
    • Mr. Johnson, what time is the meeting?

    Use commas to separate brief interjections. For example:

    • The doctor said that, no, the woman does not have cancer.
    • You would never kick the kitty, would you?
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    Printable Download

    The accompanying printable reference sheet of the rules for using commas in English is available for download: The Use of Commas in Written English Reference Sheet.

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