Comma — Usage and Examples
Comma
Commas can separate words, phrases, and clauses while indicating the importance of information within a sentence. Typically, they indicate a brief pause, allowing a reader to connect information before and after the punctuation mark.
Rules for comma usage
Because of their many functions, commas are one of the most misused punctuation marks. The following comma rules detail their correct usage.
Independent clauses: Insert a comma before a coordinating conjunction (for, and, nor, but, or, yet, so) that separates two independent clauses (phrase with a subject and a verb that can stand alone as a complete sentence).
John enjoyed the winter, but he was nervous about driving in the snow.
Introductory phrases: An introductory phrase is a dependent clause that provides background information or introduces the main clause. When there is an introductory phrase at the beginning of a sentence, separate it from the main clause with a comma.
After running through the park all day, Laura was tired.
Items in a series: When a list contains two or more words, phrases, or clauses, use a comma to separate items. The final comma after the last item in a series is called a serial comma or Oxford comma.
Shawn had to stop by the grocery store for eggs, bread, and milk.
Nonrestrictive clauses: A nonrestrictive clause (a type of relative clause) adds additional information about something already mentioned in the sentence. The information is nonessential; therefore, it can be removed without changing the meaning of the sentence. These clauses typically begin with "which" or "who" and should be set off by commas.
The dinner, which was less expensive than expected, ended with coffee and pie.
Appositives: An appositive (noun or noun phrase that precedes or follows another noun for descriptive purposes) should be placed between commas unless it starts or ends the sentence.
Jax, my golden retriever, escaped the backyard.
Interrupters or parenthetical elements: Use commas around interrupters or parenthetical elements (words or groups of words that contain nonessential information) in the middle of a sentence.
He was, generally speaking, a happy child.
Direct address: When a speaker addresses a particular person or group, they use a direct address. Place a comma after a direct address that starts a sentence and before one that ends a sentence.
Ladies and gentlemen, please have a seat.
Direct quotations: Place a comma after a name tag or attribution that starts a sentence with a direct quote and before one that ends the sentence.
Mr. James said, "Please quiet down."
"Please quiet down," Mr. James said.
Dates: Use commas when including the year in a date to separate it from the rest of the sentence.
On October 1, 1971, Walt Disney World officially opened.
Addresses: Commas should separate all of the elements of an address except a ZIP code.
123 Mockingbird Lane, Chicago, IL 60606
Edgar Allan Poe was born in Boston, MA, in 1809.
Titles: If a professional or academic title follows a name, separate the title with commas.
Cindy Jones, a city councilperson, won re-election.
John Smith, MD, performed the surgery.
Numbers: Numbers more than four digits long should contain a comma that separates every third number. For numbers that are four digits long, a comma is optional.
3,256,789
25,625
4500 or 4,500
Multiple adjectives: If more than one adjective modifies a noun, separate them with a comma if each can describe the noun independently. If the adjectives cannot describe the noun individually, they do not need a comma.
Comma needed: It was a long, boring car ride home.
Comma not needed: The bright orange kite flew through the sky.
The kite is bright orange, not bright and orange.
Adverbs: When an adverb like however, in fact, therefore, etc., begins or ends a sentence, set it off from the rest of the sentence with a comma. If these adverbs are in the middle of a sentence, precede and follow the adverb with commas.
However, she was excited to ride the rollercoaster.
She was excited to ride the rollercoaster, however.
She was, however, excited to ride the rollercoaster.
Comma placement
The placement of a comma varies depending upon its use.
| Usage | Placement |
|---|---|
| Independent clauses | • Before the conjunction separating the two clauses |
| Introductory words or phrase | • After an introductory phrase that starts a sentence
• Before a phrase that ends a sentence • A comma is optional if the introductory phrase is four words or fewer. |
| Items in a series | • After each item in the list, including before the conjunction that introduces the last time |
| Nonrestrictive clauses | • Placed around the nonrestrictive clause |
| Appositives | • Placed around an appositive |
| Interrupters and parenthetical elements | • Placed around the interrupter or parenthetical information |
| Direct addresses | • After directly addressing an individual or group |
| Direct quotations | • After the name tag if it precedes the quoted material
• Before the name take it after the quoted material |
| Dates | • Separate the year with a pair of commas if in the middle of the sentence
• Place a comma before the year if it ends the sentence |
| Addresses | • Place a comma after all parts of an address except the zip code |
| Titles | • Professional and academic titles should be placed between commas when following the individual's name
• Place a single comma before the title if it is at the end of a sentence |
| Numbers | • Numbers with more than four digits should have a comma placed every third number from right to left
• A comma is often considered optional with digits that have four numbers |
| Multiple adjectives | • Place a comma after each adjective only if the words can modify the noun individually |
| Adverbs | • After an initial adverb
• Before an adverb that is the end of a sentence • Around adverbs in the middle of a sentence |
Sentences with commas examples
The following sentences incorporate the appropriate use of commas:
Independent clauses
Henrietta walked to school every day, and Paul took the bus.
Jeff wasn't very hungry, so he decided not to go out for dinner.
Introductory phrase
After entering the house, the family dog jumped up onto the guests.
While driving in the snow, Nate watched for patches of ice.
Items in a series
Ian had to complete courses in English, math, and science.
Stephanie saw red, green, yellow, and blue balloons in the sky.
Nonrestrictive clauses
The concert, which was longer than expected, ended at midnight.
Mr. Jones, who lives three blocks away, decided to sell his house.
Appositives
Sally, my next-door neighbor, asked if she could swim in our pool.
The Mona Lisa, Leonardo da Vinci's masterpiece, is on display at the Louvre.
Interrupters and parenthetical elements
Rosalia, an animal lover, had three cats and a dog.
Rachel, of course, loved to read.
Direct address
Mr. Davidson, do you need any help this weekend?
Mom and Dad, I think I'm old enough for a later curfew.
Direct quotations
Oliver said, "I was extremely nervous about giving my speech."
"I would appreciate some help," Jane said.
Dates
On July 4, 1776, the United States declared its freedom from British rule.
President Roosevelt declared that December 7, 1941, was "a day which will live in infamy."
Addresses
Please mail any comments or complaints to 987 State Street, New York, NY 10001.
Friday's party is at 456 Mulberry Lane, Los Angeles, CA 90001.
Titles
Christina Madison, Ph.D., will be giving today's lecture.
Kevin Williams, the head of the education department, promoted the school's new program.
Numbers
The estimated population of the United States is 329,000,000.
Over 2,000 students graduated from Notre Dame in 2020.
Multiple adjectives
In the front yard was a small, stone birdbath.
John is selling a large, wooden, antique desk at the yard sale.
Adverbs
Therefore, we should study a little every day.
Celia enjoyed playing the clarinet, however.