A comma is used to add clarity to a sentence and to enable a reader to understand the relation of its parts more quickly.
Commas in a Series
Use commas to separate items in a series.
A series consists of three or more words, phrases, or clauses.
If all items in a series are joined by and or or, do not use commas to separate them.
Use a comma after the introductory words first, second, and so on when they introduce items in a series.
Use commas to separate two or more adjectives preceding a noun.
Coordinate adjectives are adjectives of equal rank. To determine whether adjectives are coordinate, try placing and between them. If and sounds natural, and if you can reverse the order of the adjectives without changing the meaning, then a comma is needed.
order. Therefore, a comma is needed).
Therefore, a comma is needed.)
is necessary.)
Do not use a comma before the final adjective in a series if the adjective is thought of as part of the noun.
is no comma between shimmering and American.)
If one word in a series modifies another word in the same series, no comma separates them.
Incorrect A dark, brown coat was left in the closet.
Correct A dark brown coat was left in the closet.
(Dark modifies brown, telling what shade of brown. It does not modify the noun coat.)
In general, don't use commas after numbers and adjectives of size, shape and age.
five small boats a big yellow moon a round nylon cushion the old stone lighthouse
A series consists of three or more words, phrases, or clauses.
- I will have hummus, tahini, and pita bread. [series of words]
- They found locusts in their car, on their porch, and even in their kitchen. [series of phrases]
- The drawings that Tina had dreamed about, that she had struggled to create, and that she had carefully matted were sold in a week. [series of clauses]
If all items in a series are joined by and or or, do not use commas to separate them.
- The bronco kicked and bucked and reared.
Use a comma after the introductory words first, second, and so on when they introduce items in a series.
- You'll pass three landmarks on the way to the island: first, the lighthouse; second, Star Point; and third, Lil's Landing.
Use commas to separate two or more adjectives preceding a noun.
Coordinate adjectives are adjectives of equal rank. To determine whether adjectives are coordinate, try placing and between them. If and sounds natural, and if you can reverse the order of the adjectives without changing the meaning, then a comma is needed.
- The cold, exhausted climbers returned to their camp.
order. Therefore, a comma is needed).
- This sari is a fine, beautiful silk.
Therefore, a comma is needed.)
- Many animals grow a thick winter coat.
is necessary.)
Do not use a comma before the final adjective in a series if the adjective is thought of as part of the noun.
- As the horns blared, the marchers formed a colorful, shimmering American flag.
is no comma between shimmering and American.)
If one word in a series modifies another word in the same series, no comma separates them.
Incorrect A dark, brown coat was left in the closet.
Correct A dark brown coat was left in the closet.
(Dark modifies brown, telling what shade of brown. It does not modify the noun coat.)
In general, don't use commas after numbers and adjectives of size, shape and age.
five small boats a big yellow moon a round nylon cushion the old stone lighthouse
Commas with Introductory Elements
Use a comma after introductory words, mild interjections, or adverbs at the beginning of a sentence.
Use a comma after a series of prepositional phrases at the beginning of a sentence.
A single prepositional phrase at the beginning of the sentence need not be followed by a comma unless the comma is needed for clarity.
Use a comma after introductory infinitive phrases and introductory participial phrases used as modifiers.
Use a comma after adverbial clauses at the beginning of a sentence.
Use a comma after words of phrases that have been moved to the beginning of a sentence from their usual position.
- Well, the meeting is about to start
- Wait, I think I can access this encoded computer file.
- However, the suspect refused to answer Holmes's question.
Use a comma after a series of prepositional phrases at the beginning of a sentence.
- From his seat in the senate, the emperor Augustus listened intently.
- Under the table by the fireplace, our puppy curled up for a nap.
A single prepositional phrase at the beginning of the sentence need not be followed by a comma unless the comma is needed for clarity.
- On Saturday I work until noon.
- Before the recent hit, Wicked was the group's best production.
Use a comma after introductory infinitive phrases and introductory participial phrases used as modifiers.
- To activate the system, pull the toggle switch.
- Erupting violently, Mt. St. Helen's spewed volcanic ash for miles.
Use a comma after adverbial clauses at the beginning of a sentence.
- Although asparagus is used as a vegetable, it is actually a member of the lily family.
- Since Marla visited the museum, she has been interested in Asian art.
Use a comma after words of phrases that have been moved to the beginning of a sentence from their usual position.
- The crime was apparently committed at midnight. (usual order)
- Apparently, the crime was committed at midnight. (transposed order)