Punctuation Rules: How to Use Commas?

Punctuation Rules: How to Use Commas?

Do you know where to put the commas in your sentences? Whether you are a novelist or someone who writes emails or posts on social media, it is important to know how to use commas correctly. In this post, we will explore when to use commas plus the rules and exceptions.

What is a Comma?

A comma is a punctuation mark, used especially as a mark of separation within the sentence. It marks natural breaks in our speech.

The comma is the most frequently used internal punctuation mark because it has the widest variety of uses.

When to Use Commas?

It’s easy to get confused about how to use commas correctly, but there are a few key guidelines to follow to help you know what to use.

Two Independent Clauses

A comma is a punctuation mark that separates two independent clauses. Commas are used to set off information that is not essential to the sentence’s meaning.

For example, if you were writing a list, you would use commas to separate the month from the day and the year. You also may use commas to separate independent adjectives from each other.

Sentence Pauses

Commas are also used to set off a pause in a sentence. We usually place the comma inside quotation marks, but there are also times when it is located at the beginning or at the end of the sentence.

Use a comma to set off the pause, if you have a phrase that interrupts the flow of the sentence. This can be a great way to make your sentence more concise and clear.

Conjunctive Adverbs

You may also want to use a comma with a conjunctive adverb, which is a verb that functions as both an adverb and an adjective. Generally, a comma should not be placed after an adjective, however.

Nonrestrictive Appositive

A comma should also not be used to set off an appositive, which is a pronoun that renames a noun. This type of clause is not essential to the sentence and is sometimes called a nonrestrictive appositive.

Serial Comma

You might use a comma to separate a series of items with the same function, such as a list. This type of comma is also called a serial comma. Use this comma before the first item in the series and after the last item.

how to use commas

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Comma Rules and Exceptions

There are many comma rules, but here are a few concerning dates, addresses, greetings, names, and large numbers.

1. Proper Names

We use the comma after the last part of a proper name when the last part comes first:

Martin, George R.R.
Maas, Sarah J.

2. Addresses

Commas are required between most of the elements in place names and addresses.

1. Buckingham Palace, London, England
2. King’s College, University of Toronto, Canada


1. Do not use a comma to separate street number from the name of the street. Example: 15 King Avenue
2. Do not use a comma to separate a province from a postal code. Example: 8771 Dundas Avenue, Whitby Ontario L1L 1B6

3. Full Dates

Commas are used with full dates (month, day, and year) but omitted with partial dates (month and year).

1. On January 28, 1986, the Space Shuttle Challenger broke apart 73 seconds into its flight, killing all seven crew members aboard.
2. In September 2021 Frankie Cameron wrote her first book.

No comma is used to separate parts of a date that begins with the day. Example: The atomic bomb was first dropped on 6 August 1945.

4. The Last Element

In complete sentence, a comma must follow the last element of place name, addresses, or dates.

1. He shot himself twice, once in the chest and then in the head, in a police station in Washington, D.C., with the cops looking on. – Red Smith
2. They signed the Declaration of Independence on July 4, 1776, in the United States.

5. Directly Addressed

Commas are used to set off the names of someone directly addressed in the sentence.

1. A few years ago, Mr. Sinclair, I spoke to you about the possibility of an internship.
2. Do you remember, Mandy, the time I told you about my trip to the Bahamas?

6. Titles or Degrees

We use the comma after the last part of a proper name when the last part comes first.

1. Sarah Malone, M.D., delivered the commencement address.
2. Did you hear the speech Sid Garvey, PhD., gave last week on psychology?

1. Write Jr., and Sr. without commas. Example: Sammy Davis Jr. started his singing career at age four.

7. Numbers

Commas are used to mark groups of three digits in large numbers, counting from the right.

1. Antarctica is 5,400,000 square miles of ice-covered land.
2. Jimmy won 6,250,000 betting on sports.

8. Greetings and Closings

Use commas after the greeting in a friendly or informal letter, and after the closing of the letter of any kind.

Dear Jesse,
Yours truly,

9. Before a Conjunction

The comma is used before a conjunction (and, but, for, or, nor, so, yet) linking two independent clauses.

1. Canadians watch hockey, but most of the world watches soccer.
2. Ava is not going to the meeting, nor am I.

1. Some very brief independent clauses may not require a comma. Example: We argued and then made up.

Grammar Checker

Test out a grammar checker, if you’re like me and have trouble knowing how to use commas correctly. These programs highlight any mistakes you make in your writing and provide real-time suggestions. They can also help you proofread your work, so you can be sure you’re not making any grammar mistakes. I have Grammarly (free version) connected to my email and Prowriting Aid (paid) set up everywhere else.

Final Thoughts

I hope this helps clarify when to use a comma. Just remember that with every rule comes an exception.


Until next time

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