Chapter 9.8 Comma Use
The Comma: Tricky, Mysterious, and Subjective?
People often think commas are tricky and mysterious, and while they may be tricky if we aren’t familiar with the rules, they are not mysterious at all. They are not subjective, and no matter what your third-grade teacher told you, it’s probably not a good idea to place a comma wherever you feel the need to take a breath.
There are actually some pretty clear-cut rules regarding commas, and while some rules seem to be clearer than others, at least in terms of how much most people understand, there are some basic comma rules that can help you know when and when not to use a comma.
1. With Coordinating Conjunctions
Use a comma with a coordinating conjunction when combining two complete thoughts (a sentence with both a subject and a verb).
A coordinating conjunction is a conjunction that combines two equal elements and can combine two complete sentences. We have seven coordinating conjunctions in American English:
For
And
Nor
But
Or
Yet
So
You may have heard of these referred to as the FANBOYS, which is a great way to help you remember all seven of the coordinating conjunctions.
Coordinating conjunctions can connect all kinds of words and phrases, but when they are used to connect independent clauses, we must place a comma before the coordinating conjunction, as illustrated in the following example:
Example
I am preparing for a zombie invasion, and I am building a strong zombie fort around my home.
TIP! If the coordinating conjunction does not connect two independent clauses, you would not need a comma before the coordinating conjunction, as illustrated in the following example:
I am preparing for a zombie invasion and am building a strong zombie fort around my home.
2. In a Series
Use a comma to separate items in a series (three or more things).
You should even place a comma between the last two, although some writing style guidelines now omit this comma. In academic culture, we still use the serial or “Oxford” comma, so even punctuation rules have a rhetorical context. In some situations, you may not use the serial comma, but in academic writing you should, as illustrated in these examples:
Examples
She stayed up all night watching scary movies and ate popcorn, peanuts, and chocolate.
She ran into the house, shut the door, locked all the locks, and hid under a blanket because she thought a werewolf was behind her.
3. With Introductory Phrases
Use commas after introductory words or phrases.
Subordinating conjunctions are words that connect, but unlike coordinating conjunctions, which connect equal parts, subordinating conjunctions connect dependent clauses (incomplete thoughts) to independent clauses. When you see a subordinating conjunction at the beginning of a sentence, this signals an introductory phrase, and you know a comma is coming at the end of that subordinate phrase, as illustrated in these examples:
Examples
Because his favorite team lost the Super Bowl, he would not speak to anyone about the game for two years.
Although they have stored a lot of food in their basement, I am not sure if they have enough for a zombie apocalypse.
TIP! When these same phrases appear at the end of a sentence, they are not set off by commas
He would not speak to anyone about the game for two years because his favorite team lost the Super Bowl.
I am not sure if they have enough for a zombie apocalypse although they have stored a lot of food in their basement.
Common subordinating conjunctions (dependent words): because, after, although, as, since, when, while, if, etc.
4. Interrupting Words
In conversations, you might interrupt your train of thought by giving more details about what you are talking about. In a sentence, you might interrupt your train of thought with a word or phrase called interrupting words.
When interrupting words come in the middle of a sentence, they are separated from the rest of the sentence by commas. You can determine where the commas should go by looking for the part of the sentence that is not essential for the sentence to make sense.
Examples
Example: An Italian astronomer, Galileo, proved that Earth orbited the sun.
Example: We have known, for hundreds of years now, that the Earth and other planets exist in a solar system.
5. With Quotes
Use a comma between the main discourse and a quote.
Whether you are writing dialog or setting up a quote from a source in your research essay, you should use a comma to separate the main discourse from your quote.
Examples
Example: As Bilbo Baggins said, “I like half of you half as well as I should like, and like less than half of you half as well as you deserve!”
Example: My favorite line in Shakespeare’s Macbeth is when the witches say, “Double, double, toil and trouble; fire, burn; and cauldron, bubble.”
Example: “To learn more about lions,” the zookeeper explained, “you should read the book Born Free.”
6. With Dates and Addresses
Commas are used in dates and addresses to separate specific elements for clarity.
- In dates, a comma separates the day from the year.
She was born on July 4, 2023, at a local hospital.
- In addresses, commas separate the street address, city, and state.
The package was sent to 123 Maple Street, Denver, Colorado.
Of course, there are other reasons to use commas, but the above examples are the six most common reasons.
Exercise 9.8.1
On a separate sheet of paper, rewrite the sentences and place commas in the correct locations in the sentence.
- Believe it or not the criminal was able to rob the same bank three times.
- Our professor Dr. Alamut drilled the lessons into our heads.
- We could go camping for vacation or we could go to the beach for vacation.
- I have never dealt with this client before but I know Leonardo has worked with them.
- Educator activist Malala Yousafzai once said “One child one teacher one book one pen can change the world.”
- Carlos graduated from college on May 15 2023 from Perry High School in Louisville Kentucky.
- Hesitating she looked back at the directions before proceeding.
- We’ll need to prepare statements for the Franks Chens and Smiths before their portfolio reviews next week.
- I asked my neighbors the retired couple from Florida to bring in my mail.
- “We don’t know what the future holds” explained the professor “but we have to face it with open eyes.”
Attributions
3.1 Commas is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by Anonymous via source content that was edited to the style and standards of the LibreTexts platform.
Commas is from Excelsior Online Writing Lab (OWL). This site is licensed under a CC BY 4.0.
Media Attributions
- Photo of Comma in the Moon © Excelsior Online Writing Lab (OWL) is licensed under a CC BY (Attribution) license
- Subordinating Conjuntions
