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Commas: Home

A guide to the primary uses of commas

Compound Sentences

Use commas to join two independent clauses with a coordinating conjunction (for, and, nor, but, or, yet, so):

Introductory Material

Use a comma after certain types of introductory material. A comma should be used after:

 A dependent clause preceding an independent clause:


An introductory phrase of five or more words:

A transitional word or phrase at the beginning of a sentence:


Direct Quotes

Use a comma to separate direct quotes from the rest of the sentence:


Use commas before and after the year in month-day-year dates:

Place Names

Use commas before and after the state, province, or country following a city name:

Letter Writing

Use commas for the salutation and closing of a letter:

Lists and Series

Use commas to separate:

Three or more items in a list:

Three or more phrases in a series:


Two or more equivalent adjectives modifying the same noun:



Use a comma before and after the following interrupters (material that interrupts the flow of a sentence):

A transition in the middle of a sentence:

The name or title of a person being addressed:

Non-essential Modifiers

Use commas to separate non-essential (or non-restrictive) modifiers from the rest of the sentence. These modifiers provide explanatory or descriptive information but do not change the meaning of the word they modify:

Note: Do not use commas around essential modifiers, that is, additional information that is necessary to the reader's understanding of the noun: 



Use commas between every three digits of numbers of five or more digits (except in certain types of scientific or technical writing):


Sometimes commas are necessary to clarify your meaning even if none of the comma rules above seem to apply: