A traditional rule is to use a comma whenever you'd naturally pause in a sentence, but we're not really traditional-type people.

Everyone and their brother has an opinion about how to use commas.

It's the Swiss Army knife of punctuation—good for (almost) every use.

And you know what? There isn't really a standard. Some publications, like The New York Times, use commas like they're going out of style; other publications, like US Weekly, sometimes forget they exist.

The one thing that all of these writing pros have in common? Consistency. Commas may be a party, but they aren't confetti. You can't just throw them as you please. Once you know (and judge) the rules, you can use them as you'd like—as long as you keep it consistent.


Here are the basic rule of when to use commas:

1. To separate the words in a series or list.

My grocery list included vanilla extract, pickles, and Frosted Flakes.

2. Before the coordinating conjunction (remember the FANBOYS!) when forming a compound sentence

Vance wanted to stay up late to watch King Kong, but he fell asleep at 8:30.

3. To separate a dependent clause from an independent clause when the dependent clause comes first.

If she finished her homework early, Lee would have time to play Call of Duty.

4. To set off introductory words, phrases, and clauses.

Sadly, we had to cancel our vacation to Dollywood.

5. To set off parenthetical elements like appositives, interrupters, and adjective clauses that aren't essential to the sentence's meaning.

My dentist, Dr. Cordula P. Willifarth, says I need to floss more often.

Randy, of course, is running late again.

Karen, who has a long history of kleptomaniac behavior, stole her neighbor's riding lawn mower and drove it to Wisconsin.

6. To separate dates and place names.

Oslo, Norway, is home to many mischievous trolls.

December 7, 1941, is a date that will live in infamy.

7. After the greeting in a friendly letter/email, and after the closing in all letters/emails.

Dear Uncle Phil,


8. To set off nouns in direct address.

Jack, your feet smell awful.

I told you, Tina, we have to pick up the tickets at the box office.

9. To set off direct quotations in a sentence.

"The Rangers game starts at 6:30," said Alan.

The girl behind the counter asked, "Do you want fries with that?"

10. To set off interjections.

No, you can't have a pony for Christmas.

11. To separate adjectives of equal importance.

The tall, handsome man walking toward them had to be an undercover cop.

12. In numbers of more than three digits.

1,999 22,566 525,600


Common mistakes


"Shmoop's favorite dogs are pugs, bulldogs, and basset hounds."

See that comma after bulldogs? That's called the Oxford comma, and it's one of the most passionately debated pieces of punctuation.

Don't believe us? Just try bringing up the Oxford comma in a room full of grammarians, and watch the red pens and grammar guides fly. So what is it?

The Oxford comma (also known as the serial comma) is the comma that comes before the words and or or at the end of a list. Technically, it's optional. Whether or not you want to include it all boils down to a style issue. You definitely need to use one if the sentence would be ambiguous otherwise, but most of the time, leaving it out doesn't change anything.

Personally, we're big fans. We're all about consistency, and we think the Oxford comma adds clarity to lists.


"Accepting his MVP award at the basketball team's banquet, Ernie thanked his parents, Michael Jordan and God."

No wonder Ernie was the most valuable player on the team! In this example, the absence of the Oxford comma makes it sound like Ernie's parents are Michael Jordan and God.

We're pretty sure that's not the reality of the situation. Put the Oxford comma in after Jordan, and then there's no possibility for misunderstanding; it's clear that Ernie's thanking three parties: his parents, Michael Jordan, and God.

We're sure you know that joining two independent clauses together with a comma is a run-on sentence. (And if you didn't, now you do.) But did you know that it has a special name? It's called a comma splice.

Think of Fruit Ninja: in a comma splice, the comma splits two independent clauses, just like your ninja blade splits two yummy pieces of fruit.

Or something.

So what's the problem, exactly? Well, the comma has absolutely no business taking on this task without a conjunction. It's simply not strong enough.

Fortunately, you can help the comma out by plugging in one of the FANBOYS. Or, if the two sentences are closely related in content, you can replace the ninja-comma with our next topic, the sophisticated semicolon. So many options!

And yes, we give you permission to take a break and practice your Fruit Ninja skills.


"My siblings find the neighborhood owl's hooting annoying, our dog seems to find it relaxing."


"The squirrel really wanted the acorn, but it was just out of his furry little reach."

It totally makes sense that the speaker's dog finds the owl's hoots calming. He is one of their animal brethren, after all. What doesn't make sense is the grammar in that first sentence. It's a comma splice. Why? Because it has two independent clauses split by a comma. That just goes against the laws of nature. To fix it, all you need to do is add a coordinating conjunction that makes sense in the sentence. We think yet would be a perfect fit, don't you?

The second sentence is grammatically correct. There's a comma and a coordinating conjunction, but, which is a wonderful way to join two independent clauses… and avoid the dreaded comma splice.


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