When to Use a Comma
The comma is a frequently used type of punctuation that helps separate words and ideas in a sentence. Writers can use a comma in many different ways. Below are some examples of the proper comma rules.
Comma Rules in a Series
Comma Rules: When listing three or more items, insert a comma after all of the items except the last one.

Comma Rules Between Adjectives
Comma Rules: When using two or more adjectives to describe someone or something, insert a comma between the adjectives.
Comma Rules: Generally, do not insert a comma after adjectives that indicate either a number or the size, shape, or age of something or someone.
Comma Rules with Introductory Elements
Comma Rules: Insert a comma after introductory words and mild interjections that come at the beginning of a sentence.
Insert a comma after an introductory prepositional phrase if it contains at least one additional prepositional phrase. You don’t need to use a comma if either the sentence starts with just one prepositional phrase (unless you’d naturally pause after saying it aloud) or the prepositional phrase is very short.
Comma Rules: Insert a comma after a verbal phrase that comes at the beginning of a sentence.
Comma Rules: Insert a comma after an introductory adverb or adverb clause that comes at the beginning of a sentence.
Comma Rules with Interrupters
Comma Rules: Insert a comma around parenthetical expressions—words, phrases, or clauses that interrupt other words, phrases, or clauses.
Comma Rules: Insert a comma to set off words of direct address, such as names, titles, or terms of respect.
Comma Rules with Nonessential Information
Comma Rules: Insert a comma to set off nonessential clauses, participles and participial phrases, and appositives and appositive phrases. Nonessential elements add additional information that isn’t necessary for understanding a sentence’s meaning.
Comma Rules in Compound Sentences
Comma Rules: Insert a comma before the coordinating conjunction that joins two independent clauses in a compound sentence.
Comma Rules with Quotations
Comma Rules: Insert a comma in direct quotations to set off words telling who is speaking. Always place a comma inside of a closing quotation mark.

Comma Rules in Dates
Comma Rules: Insert a comma between a day of the month and a year. If a date is part of a sentence, then insert a comma after the year as well. If only a month and a year are given with no specific day, then do not include a comma.
Comma Rules in Places
Comma Rules: Insert a comma between a city and its state, country, or province. If a place is part of a sentence, then insert a comma after each item in the place’s name.
Comma Rules in Letters
Comma Rules: Insert a comma after the salutation of a friendly letter and also after the closing of either a friendly letter or business letter.
Thank you for your gift!
It was great to see you when we were recently in town.
Tim Warner
Janine
Aunt Grace
Comma Rules in Names
Comma Rules: Insert a comma between a person’s name and any abbreviation or acronym that follows it. Many, though not all, businesses follow a similar practice by inserting a comma between their names and any accompanying abbreviations or acronyms.
Comma Rules in Numbers
Comma Rules: In numbers insert a comma after every third digit from the right. (This rule does not apply to zip codes, phone numbers, or house numbers.)