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Punctuation Series: Calming Your Comma Concerns

Welcome to the first edition of the punctuation series! Punctuation can really influence a sentence’s meaning, and different style guides have different rules for punctuation, so let’s dive into our first punctuation: the comma.

In my humble opinion, commas are probably my least favorite punctuation mark. They’re important, yes, but they don’t offer the same pizzazz to a sentence like an em dash or a good old-fashioned exclamation point. There are also so many different rules to commas (not to mention the infamous comma splice). And if you learned, like I did, to put a comma wherever you pause in a sentence, it can be really tricky to re-train yourself to follow the right comma rules.

A comma can be used in the following ways:

Comma #1 - Joining two independent clauses together with a coordinating conjunction*

The envelope was waiting for her in the mailbox, so she reached to retrieve the letter from the box.

People are often taught the acronym FANBOYS (for, and, nor, but, or, yet, so) to remember the coordinating conjunction. While useful, this doesn’t mean that these words are always preceded by a comma. For example, in the sentence above, the clause before and after “so” could be two sentences on their own: The envelope was waiting for her in the mailbox. She reached to retrieve the letter from the box.

But what if the sentence looked like this: The envelope was waiting for her in the mailbox so that she could reach it.

The last half of the sentence “that she could reach it” isn’t a complete sentence by itself, which means it’s dependent on the section that comes before it for meaning. As we will see in the next usage, a dependent clause at the end of the sentence doesn’t (usually) use a comma.

*If you don't include a coordinating conjunction, you're left with a comma splice.

Comma #2 - Separating a dependent clause from an independent clause at the beginning of a sentence

Across the field, the girls spotted a large oak tree.

but if the dependent clause comes after the independent clause, a comma is not needed.

The girls spotted a large oak tree across the field.

There are certain exceptions to this comma rule. If your sentence starts with a short adverbial phrase (In 2023 the writers went on strike), a comma is not required but also not incorrect if used. It also is largely dependent on which style guide you are following.

Comma #3 - Joining the last item of a list to a group of two or more items (serial comma or Oxford comma)

We decided to go to the park, the movies, and the mall.

If you are following a style guide that doesn’t use the Oxford comma (AP style for example), this comma rule won’t apply: We decided to go to the park, the movies and the mall. Overall, the serial comma provides clarity to your reader; this is especially helpful when you start using more complex sentences.

Comma #4 - Separating a nonrestrictive clause* from the rest of the sentence

My sister, who loves the color pink, is wearing a purple dress.

If the clause is restrictive (is essential to the meaning), commas aren’t needed:

The color that my sister loves is pink.

Determining when a clause is essential to the meaning of the sentence can be tricky, and it largely depends on the context. Let’s look at the first example.

It might seem necessary to know that the sister loves pink when the speaker of the sentence is describing her dress color. In this context, the fact that the sister loves pink is only an additional fact about her that doesn’t change the meaning of the sentence. Without that clause, the sentence would still make sense and convey the same meaning: My sister is wearing a purple dress.

In the second example, the clause “that my sister loves” is essential to the meaning of the sentence. While the sentence would still make sense without the clause (The color is pink), the original meaning is lost. You need to include the restrictive clause in order to convey the meaning of the sister’s favorite color.

*A nonrestrictive clause doesn't add essential meaning to the sentence. It's also called a nonessential clause.


And this is just a handful of comma usage and rules. If commas are something you struggle with (or even if you just need a refresher), I recommend bookmarking Grammarly’s Rules of Commas article. It’s comprehensive and really easy to understand!

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