Commas, commas, commas. They seem to appear in all the wrong places, and sometimes never appear at all. We’ve had such debates in the Writing Center about how to explain their uses to our students. How do you talk about commas without falling into indecipherable grammatical jargon?

Thanks to Patricia T. O’Conner, and her fabulous book on grammar, commas can easily be understood. So we let her tell you about them in her own words:

"Comma Sutra: The Joy of Punctuation"

From Patricia T. O’Conner, Woe is I: The Grammarphobe’s Guide to Better English in Plain English. (New York: Riverhead Books, 1996).

When you talk, your voice, with its pauses, stresses, rises and falls, shows how you intend your words to fit together. When you write, punctuation marks are the road signs (stop, go, yield, slow, detour) that guide the reader, and you wouldn’t be understood without them.

If you don’t believe me, try making sense out of this pile of words:

Who do you think I saw the other day the Dalai Lama said my Aunt Minnie.

There are at least two possibilities:

"Who do you think I saw the other day?" the Dalai Lama said. "My Aunt Minnie."

"Who do you think I saw the other day? The Dalai Lama!" said my Aunt Minnie."

Punctuation isn’t some subtle, old-fashioned concept that’s hard to manage and probably won’t make much of a difference one way or another. It’s not subtle, it’s not difficult and it can make all the difference in the world.

Uncommonly useful: The Comma

There’s nothing much to punctuating a sentence, really, beyond a little comma sense. Get the commas right, and the rest will fall into place.

Yeah, yeah, I hear you saying: What’s a comma or two – or three? How can something so small, so innocuous, be important? Well, that attitude can get you tossed into grammatical purgatory. You don’t believe it? Take a look:

Cora claimed Frank planned the murder.

Without commas, the finger of guilt points to Frank. But add a pair of commas, and Cora becomes the suspect:

Cora, claimed Frank, planned the murder.

Here’s another pair of examples with completely different meanings:

Augie quit saying he was looking for another job.

Augie quit, saying he was looking for another job.

In the first sentence, Augie quit talking; in the second, he quit his job.

The lesson: Don’t take commas for granted. They’re like yellow traffic lights. If you ignore one, you could be in for a bumpy ride.

Most problems with commas have to do with dividing a sentence into parts --- larger parts like clauses (each with its own subject and verb), or smaller ones like items in a series. Commas are also used to interrupt a sentence and insert another thought. Here’s how to get out of some of the most common comma complications.

Long and short division

Use a comma to separate big chunks (clauses) of a sentence with and between them. Tina hadn’t left the city in months, and by Friday she was climbing the walls. If there’s no and in between, use a semi-colon instead: Tina hadn’t left the city in months; by Friday she was climbing the walls.

Use commas to separate a series of things or actions. She packed a toothbrush, a blow-dryer, her swimsuit and her teddy bear. She finished packing, paid some bills, ate a few Oreos and watered the plants.

In a series, you can leave out the comma before "and". It’s just a matter of taste.

As I was saying

Use commas before and after the names of people you’re talking to: "Good-bye, Mom. Dad, be good," she said and hung up the phone. You can skip the comma before the name if all that precedes it is and ("And Mom, don’t worry") or but ("But Dad, you promised").

Use comas before or after a quotation: "Let’s see," said Tina. Or: Tina said, "Let’s see."

Let me interrupt

Use a comma after an introductory phrase if a pause is intended: As usual, she checked to make sure the stove was turned off. Of course, it always was. You see, Tina was a bit compulsive.

Use commas around an aside – information that could just as well go in parentheses: Her upstairs neighbor, the one without the tattoos, promised to collect her mail.

Use commas around which clauses: The airport bus, which was usually on time, never came. So she took a taxi, which cost her an arm and a leg.

But don’t use commas around that clauses: The bus that she had planned to take never came, so she grabbed the first taxi that she saw.