Punctuation Department · Today with The Mayor

Comma

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Comma

The Mayor teaches this column himself. Work through each capitalization job below, then take the quiz.

Separate the items in a series

A series is three or more things in a row. A comma separates each one, and a comma comes before the and. That last comma is the serial, or Oxford, comma. A date works the same way: a comma separates the day from the year, as in July 4, 2026.

In a sentence

We saw cats , dogs , and fish.

My party is on July 4 , 2026.

Now you try

Three or more items in a row, each split by a comma, with one before the and. You could try snacks, school supplies, or pets.

Put the comma before the coordinating conjunction

When two complete ideas are joined by a coordinating conjunction, a comma comes before that conjunction. The coordinating conjunctions are and, but, or, so, for, nor, and yet.

In a sentence

I ran , and I jumped.

Now you try

Each side has to stand on its own. Like: I was tired, so I rested.

Set off the part you could lift out

A nonessential part is a word group you could remove and still have a complete sentence. A pair of commas, one before and one after, sets it off.

In a sentence

My dog , Max , loves walks.

Now you try

Drop in a who or which part: My bike, which is blue, is fast.

Set off the introduction before the main idea

When a sentence starts with an opener, a comma comes after the opener and before the main idea.

In a sentence

Yes , I can come.

Now you try

Start with Yes, First, or an After ... phrase: After lunch, we played.

Every comma does one job

Series, joining, setting apart, and openers all do the same thing: a comma separates one part from another so the writing is clear.

In a sentence

We have cats , dogs , and fish.

First , we eat.

Now you try

Series, join, set apart, or introductory. Every one of them separates.