Have you ever written a sentence or an entire passage that seems to go on and on without end, so you sprinkle in a few commas and call it a day? If so, you are not alone! So many writers understand that commas are necessary, but few writers know how to use commas correctly.

In this post, you will learn when to use commas and when not to use commas to punctuate your writing with confidence.

When you’re ready, test yourself with a quiz and practice with our high-quality, standards-aligned questions here.

The Basics of Comma Usage

Why Should Writers Use Commas? 

Commas can be used for many purposes, but the primary purpose of a comma is to guide the reader through a text. 

For example:

• Jordan Peele, a comedian from the stand-up routine called Key and Peele, has directed several critically-acclaimed thrillers. 

In the sentence above, the pair of commas let the reader know that the appositive phrase inside the commas is non-essential. It is interesting, but it is not essential to understanding the sentence. Without these commas, the reader could become confused and not realize that the appositive phrase gave more information about the subject. In fact, the reader could mistakenly suppose that the appositive phrase was describing another person altogether! This is why writers must include correctly-placed commas in their writing.

How Do Writers Use Commas in Sentences?  

There are several ways that writers use commas in their sentences. 

1. Commas are used to separate non-essential information from the rest of the sentence.

For example: 

• My aunt, the one with short hair, called us on a video chat last weekend. 

In this instance, the information separated from the rest of the sentence by commas is non-essential. This means that everything in the appositive phrase (the phrase inside the commas) is unnecessary for the sentence to make sense. 

2. Commas are paired with coordinating conjunctions to separate independent clauses from each other. 

For example: 

• The narwhal was discovered hundreds of years ago, but scientists still know very little about this elusive mammal.

In this sentence, a comma and coordinating conjunction connect these two independent clauses.

Often students will mistake coordinate nouns, verbs, adjectives, and adverbs for coordinate clauses. To make sure that you do not make this mistake, read each clause on either side of the comma and coordinating conjunction carefully. 

Does each clause consist of a complete thought? If so, you must use a comma and a coordinating conjunction. 

If one clause does not create a complete thought, then a comma is not needed: only a coordinating conjunction. 

3. Commas separate an introductory dependent clause from the independent clause.

For example: 

• Whenever I go to Target, I always come home with way more than I intended. 

In this sentence, the introductory clause is separated from the independent clause through the use of a comma. This tells the reader to move their focus away from the first part of the sentence and toward the primary message of the sentence, which is contained in the independent clause. 

4. Commas are used to show emphasis, address someone directly, introduce a question tag, or to interject in the middle of a thought. 

For example:

• Emphasis: I mean, seriously, are you really thinking about dating him? 
• Direct Address: What do you have to say for yourself, Bryanna? 
• Question Tag: I am allowed to date whomever I choose, am I not? 
• Interjection: Yes, you are, but I will seriously question your judgment. 

In each example above, commas are used intentionally to show emphasis, direct address, introduce a question tag, or insert an interjection. When writers want to use energetic, lively dialogue, you will see these types of commas come into play. In the interaction above, the reader can sense the judgemental and critical tone of one friend and the defensive and cool tone of the other friend.

5. Commas separate cities and states, dates, and items in a list. 

For example: 

• Yvonne, Marcus, and I went to London, England on August 31, 2019. 

In the example above, commas are used to separate the list of friends, the city and country, and the month, day, and year in a date. 

6. Commas are used before beginning quotation marks and after ending quotation marks.

This one is especially tricky for writers in many circumstances. Whether you are writing dialogue in a narrative or quoting a reputable resource in a research paper, it is essential to know how to punctuate quotations correctly. 

If you introduce a quotation, you must separate the quote from your introduction with a comma like this: 

• Martin Luther King Jr. exclaimed, “Let freedom ring from Lookout Mountain of Tennessee.” 

If you continue a sentence after quotation marks, you must separate the quote from the rest of the sentence with a comma like this: 

After Martin Luther King Jr. stated, “We refuse to believe that the bank of justice is bankrupt,” the crowd erupted in cheers and applause.

When Do Writers Not Use Commas in Sentences? 

Commas should never be used in the following circumstances: 

1. When a dependent clause comes after the main subject and predicate of the sentence

We know that dependent introductory clauses must be separate from the independent clause by a comma. But, if that same dependent clause comes after the independent clause, no comma is needed. 

For example: 

• After graduating from college, she spent three years working on a Mercy ship. 

Vs. 

• She spent three years working on a Mercy ship after graduating from college.

2. Between compound subjects or compound verbs 

For example: 

• Mary and Joseph presented their project at the science fair. 

Vs. 

• Mary presented her project at the science fair, but Joseph had to stay home with a cold. 

Do you see the difference? In the first sentence, Mary and Joseph are considered a compound subject, so there is no need for a comma. In the second sentence, however, Mary and Joseph are in separate clauses, so a comma and coordinating conjunction are needed between the two. 

3. Between independent clauses without the help of a coordinating conjunction

This is a common error made by students and adult writers alike! When writers use a comma by itself between two independent clauses, this is called a comma splice. 

Because independent clauses are so strong-willed by themselves, they must have more than just a comma in between them.

There are two options for connecting these clauses: first, writers can use a comma and a coordinating conjunction. Secondly, writers can replace the comma with a semicolon.

Here are some examples:

• Susan’s cat ran away, and she was devastated. 

Vs. 

• Susan’s cat ran away; she was devastated.

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3 Tips for Understanding Commas

Here are some important tips to help you understand Commas: 

Tip #1. Commas are used to separate essential information from non-essential information in a sentence 

For example: 

• Ghostbusters, a 1980’s blockbuster film, is being rebooted this fall. 

In this sentence, the appositive phrase contains non-essential information, so it is separated from the rest of the sentence through the use of commas.

Tip #2. Commas often introduce quotations or questions

For example: 

• In Avengers, Loki states, “I am burdened with glorious purpose,” and his brother Thor rolls his eyes. 

In the example above, the quotation must be separated from the rest of the sentence through commas. 

Tip #3. Commas help differentiate between items in a list, between cities and states, and between months, days, and years in a date

For example: 

On July 13, 2013, Alicia, Mark, and Charlie visited Colorado Springs, Colorado.

In the example above, the month, day, and year are separated by commas and the list of three people and the city and state.

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Applying the Basics: Comma Review & Practice

Now that you understand how commas function in sentences, you should review the anchor chart below and complete the review to make sure you fully understand how to use and recognize commas.

The Ultimate List of Comma Rules

Refer to the graphic below to learn the different ways that commas are used in sentences:

This list does not include all possible examples of commas being used in sentences; it is meant to be used as a guide while identifying when and where to use commas.

Comma Exercises and Review 

Now that you know some common ways to use commas in sentences, test your ability to know where to place commas in the sentences below.

Select where to best place a comma in the sentences below. Remember, commas can be used in many different ways, so if you are unsure, refer back to the comma rules listed above. 

1. Harold my pet turtle is over twenty years old. 

In this sentence, commas are needed to separate the appositive phrase, my pet turtle, from the rest of the sentence since it is nonessential. 

2. While I was sleeping aliens abducted my pet squirrel. 

In this sentence, a comma is needed to separate the introductory dependent clause, while I was sleeping, from the rest of the sentence. 

3. She wanted to create something from scratch for her new cousin so she sewed him a baby quilt. 

In this sentence, a comma is needed before the coordinating conjunction, so in order to connect the two independent clauses. 

4. Don’t forget–my birthdate is April 2 2001! 

In this sentence, a comma is needed between the day and year within the date, April 2, 2001.

5. Write a sample sentence and underline the grammatical concept 

In this sentence, italicize the grammatical concept and explain 

Pro tip: Commas can be used in a multitude of ways, so it can be difficult to remember every comma rule! When in doubt, review the rules above, and remember that commas are an excellent tool for us as writers. They allow us to guide our readers through our writing, whether we are letting them know when important information is coming up or keeping information organized.

For additional practice, check out our commas content on Albert.

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Try for Yourself: Commas Quiz 

Feeling confident in your understanding of Commas? 

Take this short six-question quiz to see what you’ve learned:

1. Can a comma be used alone between two independent clauses? 

• Answer: No
• Correct Explanation: That’s right! A comma cannot connect two independent clauses alone; it must be connected to a coordinating conjunction.  
• Incorrect Explanation: Sorry, that’s not right! Remember,  a comma cannot connect two independent clauses alone; it must be connected to a coordinating conjunction.  

2. If an appositive phrase is essential to understanding the sentence, is it separated from the rest of the sentence by commas? 

• Answer: No
• Correct Explanation: That’s right! Essential appositive phrases should not be separated from the rest of the sentence by commas. Non-essential appositive phrases should be separated because the sentence makes sense without them.
• Incorrect Explanation: Sorry, that’s not right! Remember, essential appositive phrases should not be separated from the rest of the sentence by commas, but nonessential appositive phrases should be separated, because the sentence makes sense without them.

3. Where should a comma be placed in the following sentence?

Coincidentally my birthday is on March 11th as well.

• Answer: After coincidentally
• Correct Explanation: That’s right! Because the writer wants to emphasize the first word of this sentence, it is separated from the rest of the sentence with a comma.
• Incorrect Explanation: Sorry, that’s not right! Remember, if a writer wants to emphasize a word in a sentence, that word is separated from the rest of the sentence with a comma.

4. Where should a comma be placed in the following sentence? 

You brushed your teeth today right?

• Answer: Before right
• Correct Explanation: That’s right! Commas must be used to separate question tags like “right” from the rest of the sentence.
• Incorrect Explanation: Sorry, that’s not right! Remember, commas must be used to separate question tags like “right” from the rest of the sentence.

5. Where should a comma be placed in the following sentence? 

Scout said “Hey, Boo.” 

• Answer: before the quotation marks
• Correct Explanation: That’s right! A comma is needed before the quotation marks in order to introduce Scout’s quote. 
• Incorrect Explanation: Sorry, that’s not right! Remember, commas are needed before and after quotation marks to separate them from the rest of the sentence.

6. Where should a comma be placed in the following sentence?

I wanted to be the lead in the play but my friend was chosen instead.

• Answer: before “but”
• Correct Explanation: That’s right! A comma is needed before the coordinating conjunction, but in order to correctly separate these two independent clauses.
• Incorrect Explanation: Sorry, that’s not right! Remember, a comma and a coordinating conjunction is needed to separate independent clauses from one another.

For additional practice with commas,  check out our practice on Albert: Commas.

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Teacher’s Corner for Commas

While correct punctuation is just as important as proper grammar usage, it is easy to let punctuation fall by the wayside and focus more heavily on grammatically correct sentences. However, knowing how to use commas correctly is just as important as knowing how to use parts of speech, clauses, and phrases properly, because commas allow our writers to keep their writing organized and flowing smoothly. The Common Core English Language Progressive Skills Chart is a great tool for teachers when establishing where their students’ understanding may fall when it comes to commas.

For specific standards on the different ways to use commas, check out the Common Core State Standards site.

Albert’s Comma Practice provides a large bank of review questions organized into subtopics for more focused comma review and practice. Our assessments can then give teachers a broader look at student understanding of commas and other grammatical concepts.

Summary for Commas

Commas can be used for many purposes, but the primary purpose of a comma is to guide the reader through a text. 

Commas are:

1. used to separate non-essential information from the rest of the sentence.
2. paired with coordinating conjunctions to separate independent clauses from each other. 
3. used to separate an introductory dependent clause from the independent clause.
4. used to show emphasis, address someone directly, introduce a question tag, or to interject in the middle of a thought. 
5. used to separate cities and states, dates, and items in a list. 
6. used before beginning quotation marks and after ending quotation marks.

Be sure to check out our grammar course for more comma practice. 

You can also access over 3,400 high-quality questions that address nearly every grammatical concept.

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