10.09: Comma rules simplified

Let’s talk about commas. One of the hardest things in proofreading is commas. This is because often, unlike with other punctuation, commas are often only placed based on style considerations, or audience considerations. In other words, the rules are sometimes more flexible.

Here is one good rule you should know about commas: Use commas in between items in a series:

Bob likes ice cream, ham sandwiches, and pickled herring blended together into a shake.

Do you need the comma before “and” in the list? Do as your instructor says. Generally, it’s not wrong to have it, but if the items in the list will be at all confusing for the reader without it, include it.

Another rule is: Use commas to separate out extra information from the rest of the sentence (commas with introductory phrases, transitional expressions, parentheticals, appositives, nonrestrictive clauses). This is information that, if removed, will not change the basic meaning of the sentence:

I find lutefisk disgusting, despite what you say about it.

Mighty Ducks, that movie that stars Emilio Estevez, was filmed in Minneapolis.

Hey, did you listen to Manuela’s speech?

Rhonda, who constantly forgets things, left her jean jacket on the couch.

After the movies, Don and Janice danced the electric boogaloo to some classic Prince.

Margarita, the best Jell-o salad maker in all the land, forgot to buy mandarin oranges.

Tim accidentally shaved off an eyebrow, which turned out to be a good look for him.

What about other connections in sentences? You can use commas to indicate that the end of the “subordinate” or “modifying” thought is done. That is, use commas in coordination and subordination:

Even though he wandered around the mall for hours, Javier couldn’t find the perfect pair of shoes.

I got sick of waiting for him, so I went out to the car.

In the first example, the clause “even though…” is modifying, or giving information about, why and under what circumstances Javier “couldn’t find” (the main subject and verb of the sentence). In the second, the comma is used in conjunction with the word “so” to move to the second section of the sentence, which is a section that indicates results of the main subject “I” and the verb “got sick.” Again, notice that the hinge of the sentence is the main subject and main (or governing) verb, and the other things in the sentence, including very long clauses or phrases, are just giving more information about (modify) that basic thing indicated by the subject and verb.

Use commas to separate out two coordinating adjectives that describe the same noun:

He is a silly, fun kid.

Note: silly and fun are of the same “weight” or importance and are therefore coordinating. You could easily say “He is a fun, silly kid” and the sentence makes sense—that’s how you know they’re coordinating and need a comma between them. Here’s an example of non-coordinating adjectives:

That ridiculous foam rubber clown nose is in the garbage.

You wouldn’t say, “That foam rubber ridiculous clown nose…” This means that “ridiculous” and “foam rubber”—and “clown,” for that matter—are of different weight, so the adjectives need to be presented in that order in the sentence, thus making them non-coordinating.

There are also some other smaller, but still important, comma rules that you should know about.

Use commas after a city and the state in a sentence:

The population of Minneapolis, Minnesota, is over 400,000 people.

Use commas to separate items in a date:

He was hired Tuesday, March 30, 1987.

Use commas to separate items in an address:

I live at 123 Maple Street, Rochester, Minnesota.