By the time I finished collecting diplomas for completing high school, my bachelor’s degree, and my master’s degree and spending 15 years editing daily newspapers, I thought I understood the comma pretty well.
When I started editing non-fiction book manuscripts, I realized that I didn’t know much of anything about the comma. The people I was working for did know all about the comma, and I had to improve my game quickly.
I was on my way to a bad case of tennis elbow by constantly reaching for the heavy Chicago Manual of Style to look up comma rules. It was also tedious and time-consuming. So I made a cheat sheet, condensing most of Chicago’s picky comma rules onto a single sheet of paper, which I posted in plain sight. (It was not the only cheat sheet I made to save myself time and heavy lifting. Why there should be different styles for endnotes and bibliography remains a mystery.)
Below is my aide-mémoire for exacting comma use, offered for your use. Again, this is taken from the Chicago Manual of Style, 5th ed. If you’re writing or editing for a publication or company, you’ll need to use whatever stylebook you’re told to. Such books are often at odds with each other. Don’t take any of it personally; just do the job the way the people writing the checks want it done and be happy.
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Comma rules
* Use commas to separate words, phrases, or clauses in a series.
The flag was red, white, and blue. I came, I saw, I conquered. They walked, ran, and rode to their destinations.
* Use commas to list adjectives in a series if they are of equal importance.
(If you could say the word “and” between each adjective, use a comma. If not, don’t.)
They live in a large, modern two-story home.
* Use commas before coordinating conjunctions (and, but, or, nor, yet, for, so) to join two independent clauses.
(This means having two independent clauses joined by a coordinating conjunction to create a compound sentence.)
He had no proper breeding, and he lacked spirit.
* Use commas to set off introductory elements.
Adverb: First, I need to go to the bank.
Prepositional phrase: After dinner, let’s watch a movie.
Appositive (a noun cluster that specifies another noun in the sentence): A lazy dog, Norman had no interest in chasing cars.
Participial phrase (a verb form that modifies a noun or pronoun): Unmoved by his coworkers’ pleas, the boss’ son decided to rat them out.
Infinitive phrase (to followed by a verb): To be honest, I can’t stand the sight of him.
Dependent clause: If you’re going to town, I am going with you.
* Use commas to set off strong pauses in the middle or at the end of a sentence.
Appositive: Janet, the mother of six, changed lots of diapers.
Conjunctive adverb (an adverb that modifies the whole sentence): The robber, nevertheless, took the things of sentimental value.
Prepositional phrase: That barber is, without a doubt, the handiest with a razor.
Participial phrase: The dog, hidden by the trees, watched the duck.
Direct address: When you go, Fred, take that with you.
Parenthetical clause: I prefer red, of course, but blue will be fine.
Nonrestrictive clause (a clause not necessary to understand the meaning of the sentence): The cat, which had never before seen a mouse, leaped to the hunt.
* Use commas to set off complete quotations.
* Use a comma whenever doing so will prevent confusion.
