Commas

Oh, commas. Love them or hate them, they’re everywhere. You could write without ever using one, but it would be a serious challenge that’s usually reserved for very basic reading levels. So, if we have to live in a world with commas, why not learn when to use them?

Restrictive vs Non-Restrictive Elements
To simplify, you can remember the difference between ‘that’ and ‘which.’ My cat, which is black, ran down the stairs. The blackness of my cat has nothing to do with the action running down the stairs, but it’s a nice detail. My cat could just as easily have been another color, and it wouldn’t have changed the action. The ‘which’ is known as a non-restrictive element.

Conversely, a restrictive element is necessary for the sentence and usually signaled by ‘that.’ My cat, which is black, ran down the stairs that led to the zombies. Here, the reader needs to know that the stairs led to the zombies, either to differentiate from other stairs that led somewhere else or to explain why the narrator told you what the cat was doing.

‘Which’ and ‘that’ aren’t the only examples of restrictive and non-restrictive elements, but they’re a good way to tell what you’re working with. Think to yourself: if I removed this part of the sentence, would my meaning still be clear? If yes, it’s non-restrictive. If no, it’s restrictive.

Introductory Elements
Most people tune out in English class when the teacher starts talking about independent and dependent clauses, but they’re actually pretty simple. This is an independent clause. Subject (this) verb (is) object (an independent clause). When I wake up is a dependent clause because even though there’s a subject (I) and a verb (wake up), there’s no object. When I wake up…what?

All of that to say: it’s fun to start a sentence with a dependent clause. When I wake up, I cuddle my cats. See how there’s a comma after the dependent clause? That’s because it can’t stand on its own.

Comma Splice
They’d been dead for days, the body stank to high heaven. This is what’s known as a comma splice, and it happens pretty often, especially in fiction. Publishers may allow it as an authorial quirk, but technically, using a comma to join two independent clauses is incorrect. You might have noticed I used one in my introduction. If you want to adhere to grammar rules, you have two options:

They’d been dead for days. The body stank to high heaven. (Independent clauses are separated.)

OR

They’d been dead for days, and the body stank to high heaven. (Independent clauses are joined using a comma and a conjunction.)

Oxford Comma
I’m Team Oxford Comma all the way. I will always recommend using them for extra clarity, but you don’t have to. Most style guides have no preference as long as you’re consistent. To me, it just looks better to have a final comma in a list (bananas, eggs, and milk vs. bananas, eggs and milk), but not everyone agrees. What do you think?