Commas
Items in a Series
1. Use commas to separate items in a series.
Do not use a comma before the first item or after the last item in a series.
WORDS
- The cups, saucers, glasses, and dishes have been washed. [Each of the nouns in the list is a separate item, so commas separate the nouns.]
PHRASES
- The dog ran down the street, across the yard, and through the gate. [Each of the phrases in the list is a separate item, so commas separate the phrases.]
CLAUSES
- The heater is on, the doors are closed, and the room is warm. [Each of the clauses in the list is a separate item, so commas separate the clauses.]
When and, or, or nor joins all the items in a series, do not use commas to separate them.
EXAMPLES
- Paul and Roger and Margaret were all selected for the leads in the play. [And joins all the items in the series, so commas do not separate the items.]
- The missing keys must be on the counter or in the cabinet or under the sofa. [Or joins all the items in the series, so commas do not separate the items.]
2. Use a comma to separate two or more adjectives preceding a noun.
EXAMPLE
- The green, lush hills were beautiful against the blue, clear sky. [Green and lush describe hills and are separated by a comma. Blue and clear describe sky and are separated by a comma.]
EXAMPLE
- A small, new French restaurant is on Richmond Avenue. [Small and new are both adjectives describing French restaurant, so a comma separates them. French and restaurant are thought of as part of the same noun, so no comma comes before French.]
EXAMPLE
- It was a bright, sunny morning. [Bright and sunny are adjectives describing morning, so a comma separates them.]
- He’s wearing a bright green jacket. [Bright describes the adjective green, so bright is an adverb. No comma is needed between bright and green.]
Independent Clauses
3. Use a comma before a coordinating conjunction (and, but, for, nor, or, so, or yet) when it joins independent clauses.
EXAMPLES
- Sandy skated to the park, and Marcus rode his bike. [The two groups of words are independent clauses that are joined by and.]
- Dad repaired the fence, but Mom mowed the lawn. [The two groups of words are independent clauses that are joined by but.]
REMINDER
An independent clause is a group of words that has a subject and a verb, expresses a complete thought, and can stand by itself as a sentence.
A compound sentence has two or more independent clauses. Do not confuse a compound sentence with a simple sentence that has a compound verb.
A compound verb is two or more verbs that are joined by a conjunction and share the same subject.
A simple sentence does not need a comma before the conjunction that joins its verbs.
EXAMPLES
- The chipmunk (S) grabbed (V) the pecan, and he (S) shelled (V) it with his paws. [This compound sentence has two independent clauses joined by the conjunction and, so a comma is used before and.]
- The dog (S) jumped (V) in the air and caught (V) the ball. [This simple sentence has only one subject and a compound verb, jumped and caught. The sentence has only one independent clause. No comma is needed.]
Nonessential Elements
4. Use commas to set off nonessential subordinate clauses and nonessential participial phrases.
A nonessential subordinate clause adds information to a sentence but is not necessary to the meaning of the sentence. A nonessential subordinate clause can be removed from the sentence without changing its basic meaning.
EXAMPLE
- Our teacher, who is an author, helped us begin our essays. [Who is an author is a nonessential subordinate clause. It adds information about teacher and can be removed from the sentence without changing the basic meaning of the sentence.]
REMINDER
A subordinate clause is a group of words that has both a verb and its subject but does not express a complete thought.
An essential subordinate clause contains information that is necessary to the meaning of the sentence.
An essential subordinate clause is not set off by commas.
EXAMPLE
- The boys that are standing by the lockers are my cousins. [That are standing by the lockers is an essential subordinate clause that tells which boys are being discussed.]
A nonessential participial phrase adds information to a sentence but is not necessary to the meaning of the sentence.
A nonessential participial phrase can be removed from the sentence without changing its basic meaning.
EXAMPLE
- Warmed by the sun, the streets steamed after the rain. [The participial phrase Warmed by the sun adds information about streets but can be removed from the sentence without changing the basic meaning of the sentence.]
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REMINDER
A participial phrase is a group of words that begins with a present or past participle. The entire phrase is used as an adjective.
An essential participial phrase contains information that is necessary to the meaning of a sentence.
Essential participial phrases are not set off by commas.
EXAMPLE
- The man jogging around the park is my father. [The participial phrase jogging around the park is necessary to the meaning of the sentence. The phrase is not set off by commas.]
Introductory Elements
5. Use a comma after certain introductory elements.
Use a comma to set off introductory words such as yes, no, well, or why at the beginning of a sentence.
EXAMPLES
- No, the plants haven’t been watered yet.
- Well, I think it is time to leave.
Use a comma after an introductory participle or participial phrase.
REMINDER
A participle is a verb form usually ending in –ing or –ed that is used as an adjective.
A participial phrase is a group of words that begins with a participle and is used as an adjective.
EXAMPLES
- Pouncing, the cat landed on the toy mouse. [The introductory participle Pouncing is set off from the rest of the sentence by a comma.]
- Frozen by the winter cold, the lawn had turned yellow. [The introductory participial phrase Frozen by the winter cold is set off from the rest of the sentence by a comma.]
Use a comma after two or more introductory prepositional phrases or after one long introductory prepositional phrase.
EXAMPLES
- In the fields next to the school, we found a jacket. [The two introductory prepositional phrases are followed by a comma.]
- After hard work and perseverance, we won the championship. [The long introductory prepositional phrase is followed by a comma.]
Use a comma after an introductory adverb clause.
An adverb clause is a group of words that has a subject and a verb, cannot stand alone as a sentence, and tells where, when, how, or to what extent about another word in the sentence.
An adverb clause begins with a subordinating conjunction such as as soon as, although, after, because, if, when, or while.
EXAMPLES
- As soon as Ashley gets here, we will leave for the recital. [The introductory adverb clause is followed by a comma.]
Interrupters
6. Use commas to set off an expression that interrupts a sentence.
Use commas to set off nonessential appositives and appositive phrases.
An appositive is a word that is placed beside another word to explain or describe it.
An appositive phrase is a group of words that includes an appositive and any of the modifiers of the appositive.
A nonessential appositive or appositive phrase adds information to a sentence but is not necessary to the basic meaning of the sentence.
EXAMPLE
- My cousin, the athlete, draws very well. [The appositive phrase the athlete adds information about cousin but is not necessary to the meaning of the sentence.]
An essential appositive or appositive phrase adds information that is necessary to the meaning of the sentence.
An essential appositive or appositive phrase is not set off from the rest of the sentence by commas.
EXAMPLE
- My friend Carmen invited me to dinner. [The essential appositive Carmen is not set off from the rest of the sentence by commas.]
Words used in direct address are set off by commas.
Direct address names the person or persons spoken to in a sentence.
EXAMPLE
- Marcellus, could you come here please? [Marcellus is direct address, so it is set off from the rest of the sentence by a comma.]
Parenthetical expressions are set off by commas.
Parenthetical expressions are side remarks that add information or show relationships between ideas in a sentence.
Some common parenthetical expressions are after all, by the way, for instance, however, meanwhile, and therefore.
EXAMPLE
- He was, after all, an excellent violinist. [After all is a parenthetical expression, so it is set off from the rest of the sentence by commas.]
Conventional Uses
7. Use commas in certain conventional situations.
Use commas to separate items in dates and addresses.
Do not use commas to separate a month from the day of the month, the day from the month when the day comes before the month, or the month from the year when no day is given.
EXAMPLES
- The graduation ceremony will be on Friday, May 18, 2009. [Commas are used to separate items in the dates, but a comma does not separate the month from the day of the month.]
- The reunion is scheduled for 19 November, 2010. [A comma separates the month from the year, but no comma separates the day from the month.]
- The new bridge should be completed by July 2010. [Commas are not used between the month and the year when no day is given.]
Do not use commas to separate a house number from a street name, a state name or abbreviation from a ZIP Code, or items joined by prepositions.
EXAMPLES
- We once lived at 1325 Newcreek Lane. [Commas are not used between the house number and a street name.]
- Send the package to 4217 Woodrow Avenue, Raleigh, NC 44873. [Commas are not used between the two-letter state abbreviation and the ZIP Code.]
- The new museum is at 637 Karen Avenue in Manchester. [At and in are prepositions. No commas are used between items separated by the prepositions.]
Use a comma after the salutation of a personal letter and after the closing of any letter.
The salutation is the short line at the top of a letter in which you greet the person you are writing.
The closing is the short line at the bottom telling the person that the letter is about to end.
EXAMPLES
- Dear Macy,
- Yours truly,
Use a comma to set off a title, such as Jr., Sr., or Ph.D., that follows a person’s name.
EXAMPLE
- Roger Baldwin, Jr.