When To Put Commas

English is hard. Sometimes at least. This is why I covered the rules for putting commas in this article.

These times include using commas, at least for me as I am not native to English. This article serves primarily as a reminder for me when I forget this stuff again. It primarily states rules for American English (as it is most popular).

Separating Independent Clauses

Commas are put between two independent clauses which are joined by a coordinating conjunction (like and, but, yet, etc.) if they have two separate ideas.

Examples include:

• John walks down the hallway, and he is tall.
• I watch a movie, or I go take a bath.

But, separating subject and verb is not allowed. If I left out the second I in the last sentence, I would need to remove the comma.

Separating Introductory Clauses

Introductory clauses or phrases like If… or But… are separated by a comma from the main part of the sentence.

Examples include:

• When I was a child, I yearned for the mines.
• But since you already did the assignment, I felt no need to start.

The Oxford Comma / Enumerations

Being controversial, I like to use it. It is put after the second-to-last term in an enumeration with three or more terms.

Examples include:

• I got beans, greens, and potatoes.
• Do you want ice cream, pizza, or soda?

Injecting Irrelevant Information

Sometimes, you want to add a little side-fact to a sentence that has nothing to do with the main idea. These nonessential clauses are called nonrestrictive.

Examples include:

• Elon Musk, who has invested in Tesla, owns StarLink.
• Peter, whose meatballs you like, ran a marathon last Sunday.

Once the idea is relevant for the main clause, you don’t put commas.

Appositives

If the added restrictive clause is a noun or a noun phrase that renames a nearby noun, it is called an appositive.

Examples include:

• Elon Musk, (an) investor of Tesla, owns StarLink.
• Peter, (a) chef, is 42 years old.

Direct Addressing

If you are addressing someone in your sentence, the person you are addressing is surrounded by commas.

Examples include:

• Knock it off, John!
• To be quite frank with you, Susan, I never considered this.
• Peter, may you repeat that?

Commas Surrounding Quotations

Commas are being put before and after a direct quote. The comma placement, however, depends on what English flavor you choose, American or British:

In American English, commas that belong to the sentence structure outside of quotations are included in the quotation marks. Examples include:

• “Knock it off,” Peter said.
• But, since Peter said, “knock it off,” I liked him even more.

…which seems unlogical to me. Luckily, in British English this is fixed. Examples include:

• “Knock it off”, Peter said.
• But, since Peter said, “knock it off”, I liked him even more.

Commas With Data

Dates

In dates, the year is set off with a pair of commas. Example:

On January 1st, 2000, a new century began.

Addresses

Commas separate elements in an address. However, no comma is put before a ZIP code. Example:

This scene takes place in Liverpool, England, in 1970.

Numbers

Commas are used in numbers to make them visually more appealing. Every three digits a comma is inserted. If the number is four digits long, a comma is optional. Examples include:

• 1234 meters
• 1,234 meters
• 299,792,458 meters per second

That wraps it up, I guess. Punctuation is hard, and I thank JetBrains for the awesome IDEs that have built-in gramma checking that catches every missed, or unnecessary, comma.

When writing this article, I had assistance from this worksheet.