Hello, Write Owls. Welcome to Day Ten of Grammar 110. Today we’re covering commas.

How many of you are terrified of commas? Commas are probably the hardest punctuation mark to learn. They’re used in many different ways, so there are lots of rules associated with them. I’m going to explain the rules as clearly as I can and guide you through some examples. I myself had trouble with commas until I was a junior in high school, so I understand how difficult learning the rules can be. I hope I can shed some light on this tricky subject for you.

Commas have a lot of functions, so I’m going to go through them one-by-one.

Commas are used to divide words in a series, or list. The final comma is called the Oxford comma, and it is optional. I personally use the Oxford comma because I believe it helps with clarity.


I went to the store to buy milk, bread, and eggs. (With Oxford comma)

I went to the store to buy milk, bread and eggs. (Without Oxford comma)

She likes pizza, tacos, fish and chips. (There could be confusion as to whether she likes fish and chips as separate foods or as a dish.)

She likes pizza, tacos, fish, and chips. (This clarifies she likes the foods separately.)

She likes pizza, tacos, and fish and chips. (This clarifies she likes the dish fish and chips.)

Commas separate compound sentences. I had trouble with this rule, but there’s a simple trick I use now that helps me. (If you don’t know what a compound sentence is, refer to my lesson here.) If the words before the coordinating conjunction are a full sentence and the words after the coordinating conjunction are a full sentence, you use a comma. If one of the sets of words is not a full sentence, you don’t use a comma.


I write books, and I study archaeology. (“I write books” is a complete sentence. “I study archaeology” is a complete sentence. The comma is necessary.)

He likes walking and doesn’t like running. (“He likes walking” is a complete sentence, and “doesn’t like running” is not a complete sentence. There shouldn’t be a comma.)

In short compound sentences, the comma is not required. The first example in this section is short enough it doesn’t require the comma.

When a sentence has the word or and it is being used to give a definition, set it off with a comma.


The tome, or a large book, was very old.

I want to be an anthropologist, or someone who studies humans.

If the sentence starts with a dependent clause or introductory phrase, you separate that clause from the independent clause using a comma. (If you don’t know what phrases and clauses are, see my lesson here.) If these clauses appear at the end of the sentence, do not use a comma.


If you want to go to university, you have to have good grades.

You have to have good grades if you want to go to university. (The dependent clause is at the end, so there is no comma.)

When the movie was over, we went home.

At last, they made it to their destination.

Stretching his arms, he reached for the box on the top shelf.

Afterthoughts are separated by commas, except for the word too. I was originally taught to offset too with commas, so I’m still terrible about doing this one correctly.


You’ve written novels, haven’t you?

They want to write novels too.

Anything that interrupts the sentence should be separated with commas. This can be added information, the word too when it means also, and abbreviations like e.g. and etc.


The book, which was written a hundred years ago, is falling apart.

I, too, want to write novels.

She writes in three genres, i.e. romance, contemporary, and historical fiction.

Commas separate two adjectives if it makes sense to put the word and in between them.


He reads old, dusty books. (“He reads old and dusty books” makes sense, so there is a comma.)

She is wearing a dark green sweater. (“She is wearing a dark and green sweater” doesn’t make sense, so there is no comma.)

Commas set off names when the person is being directly addressed, and they set off titles including academic degrees.


Do you write novels, Jess?

Indiana Jones, PhD, is a famous archaeologist.

Dr. Henry Jones, Jr. is a famous archaeologist.

Commas separate contrasting expressions and help clarify sentences that are otherwise confusing.


He likes animals, but not snakes. (These are contrasting ideas.)

Wherever he is, I hope he’s safe. (Typically written, “I hope he’s safe wherever he is.”)

There are other comma rules, but they aren’t as misused as these ones, and they don’t show up in creative writing as frequently. The last thing I want to talk about is a comma splice. A comma splice is when two independent clauses are joined with only a comma. There are three primary ways to correct a comma splice.


Incorrect: I write books, I study archaeology.

Correct: I write books, and I study archaeology. (Add a coordinating conjunction.)

Correct: I write books. I study archaeology. (Make them two sentences.)

Correct: I write books; I study archaeology. (Replace the comma with a semicolon.)

That’s all I have on commas for you. With practice and time, you can understand comma rules. That doesn’t change how complicated they are. Even I’m not perfect when it comes to commas. If you have any questions, let me know in the comments down below, and I’ll answer them either as a reply or in my Q&A on Saturday.

For practice, see if you can determine where the commas go in these sentences. You can share your answers in the comments if you want me to check them.

1. After much study Henry Jones Jr. PhD became a world-renowned archaeologist.

2. Actually the large hairy dog is very sweet and loves people.

3. She went to Spain France and Germany.

4. He gave the watch which was very old to his son for his birthday and he bought him a new phone too.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: