Now before you enter the terrifying world of the comma, you must remember one thing: the basic purpose of all punctuation is to help make text easier to read. Punctuation creates signposts for the reader. Punctuation alerts you that you’ve stumbled into someone’s spoken words, and then when you’ve stumbled back out. Punctuation alerts you to the end of a complete thought. Punctuation helps you sort out groups of things. Punctuation helps the reader’s brain process. Punctuation is your employee, whose job is to keep the reader from becoming confused.

Sure, it’s a pinch-faced grumpy employee sometimes with a complicated job description, but once you work out what tasks you can give each punctuation mark – your task of crafting readable manuscripts becomes much easier. For now, let us consider the comma.

COMMAS HELP KEEP GROUPS OF THINGS FROM GLOBBING TOGETHER

Have you ever had a jewelry box where you tossed everything? When you wanted to wear a necklace, you had to untangle it from all the other junk. Some people write that way. They glob everything together, and the reader has to try to sort it out. That’s where the handy serial comma comes in. It separates the items so you can easily pick them out.

Serial commas are used when you have a series of three or more things in a sentence:

Jake pulled a bottle cap, a quarter, and a piece of string from his pocket.

Penny ate a cookie, brushed her teeth, and settled down to play on the computer.

Notice how the commas help you easily pick out each item. If you only have two items, they don’t easily tangle. With just two things, you do not need a comma:

Mark carried a sandwich and a book to the coach.

Fred washed the dog and mowed the lawn before dinner.

Mostly we know that, but sometimes we add a bunch of other stuff to the sentence and get a little confused. Are we really only combining two things? And our little fingers itch to add a comma. Resist the itch. If you only have two things in a series, you do not need a comma:

Mark carried a rare roast beef sandwich and a half-read book to the couch.

Fred washed the dog with the stinky green shampoo and mowed the overgrown lawn around the patio before dinner.

You felt that twitchy need to add a comma didn’t you? But each sentence really only linked the two things so no comma needed.

COMMAS HELP SEPARATE TALK FROM TALKERS

Commas are used constantly in dialogue to separate the actual dialogue from the “tag line.” The tag line is the part that lets you know who is speaking. For instance:

Janet squinted at him and said, “Do I know you?”

“I think you do,” Pete answered.

Do you see how the comma landed on the “who is speaking” side in the first example and on the “what is being said” side in the second example? Which ever comes first, the speech or the speaker, the comma will keep them apart.

EXCEPT.... (Don’t you hate it when there’s an except?)

Except if doesn’t work that way when the line of dialogue is a question or an exclamation followed by the tag line. Those are the two forms of dialogue punctuation that overrule the comma. Like this:

“Could you tell me your name?” she asked.

“Don’t be stupid!” he shouted.

COMMAS ARE USED TO CAGE REMARKS THAT BUTT INTO A SENTENCE

Whenever the sentence has an interruption, you can use commas to cage off that interruption. For instance, you use commas when the sentence is interrupted by someone’s name when it is addressing the person directly:

“Jack, come here and say that,” she said. [The name “Jack” butts into the remark, so it needed to be closed off by that comma.]

“Don’t yell, Betty, because it’s giving me a headache,” he said. [The name “Betty” butts into the middle of the remark so needs to be closed off by commas on both sides.]

Just to add a little jargon to your life, dropping a name like that in the middle of a quote is called using it in “direct address.” So when someone says “direct address” to you, you can nod wisely.

Now, you can be interrupted by more than names. Sometimes the sentence is interrupted by a little bit of explanation dropped in:

Mr. Carter, the man with the strange blue veins on his head, scares me. [The blue vein remark helps you understand exactly which man is the scary one. It’s extra information dropped in.]

I gave it to the woman in the office, the one with blue eyes. [Here the extra info came at the end of the sentence so you only needed the one comma to close it off.]

These little drop-ins with extra information that help redefine the thing or person they follow in the sentence is called an appositive. It’s okay to forget that if you want. Just remember to use the commas when they break into the sentence.

When I discovered I was a brilliant writer, don’t say I’m not, I found many people felt jealous. [The side remark “don’t say I’m not” bursts into the middle of this vain little sentence so must be caged off by commas on both sides. This use is called parenthetical because it’s ALSO okay to cage it off with parentheses if your sentences are already a little comma rich or if you need that little bit of extra caging.]

Lunging and snarling at the bars of the cage, the Chihuahua terrified the burly animal control officer. [Sometimes the thing that butts into the sentence is actually at the beginning. Your sentence is clearer if you keep it separate from the main sentence with a comma, and that’s the way we do it. Plus, I often don’t think Chihuahua dogs get enough notice for being the vicious beasts they are.]

THE COMMAS YOU PROBABLY HAVE KNOWN SINCE GRADE SCHOOL

When you write addresses and dates, commas jump in to keep the elements separate and aid clarity:

I wrote this article on Saturday, June 19, 2010.

Have you ever been to Hendersonville, North Carolina?

My daughter wants to go to Paris, France.

I once lived at 2010 Southwest 42nd Street, Hollywood, Florida.

CAN I STICK THESE SENTENCES TOGETHER WITH A COMMA?

Commas form part of the glue when sticking sentence together. They are not allowed to do the whole job though. It’s a team effort, like this:

Amanda loves to wear dresses, but she rarely keeps them clean.

Pete plays baseball in the spring, and he tap dances in the winter.

Now this can fake you out and make you think you’re dealing with the two items in a series thing – you’re not. You have two sentences glued together with a conjunction and comma combination. The test to see if you’re really dealing with two sentences is to break the thing apart in your head, ditch the conjunction, and see if both halves have a subject and verb (ouch, sorry about the grammar talk…don’t hit me).

Amanda [subject] loves [verb] to wear dresses. She [subject] rarely keeps [verb] them clean.

Pete [subject] plays [verb] baseball in the spring. He [subject] tap dances [verb] in the winter.

You’ll always put the comma at the end of what WOULD be your first sentence. Then you’ll have a conjunction (and, but, because, or, etc).

DON’T SPRINKLE COMMAS LIKE FLY SPECKS

Sometimes folks just seem to hiccup a comma now and again. Mostly your commas should follow the “rules” mentioned in this article. Don’t use commas to chop up the normal part of the sentence [subject – verb – direct object].

For instance, no one really had the urge to say

The cat, ate the mouse.
The cat ate, the mouse.

Those look weird, don’t they? As a result, don’t add commas just because the sentence is starting to feel long:

The black cat with the long whiskers delicately ate the white lab mouse with the odd glowing green eyes.

The sentence is long but doesn’t need any breaking up. Nothing is butting into the sentence. No names are inserted. Nothing is popped in to redefine the characters. It’s just a decorative sentence. No commas needed. So you would NOT say:

The black cat, with the long whiskers, delicately ate the white lab mouse, with the odd glowing green eyes. [NOPE, unnecessary comma panic. Those two “with” phrases aren’t redefining your nouns. They aren’t butting in. They’re just sprucing them up a bit.]

Comma rules can seem a bit complicated at first, but if you take these comma "rules" with you into your writing, you'll find you improve clarity in your work. And it'll give you something new to catch when you're searching published books for typos! We all love to do that.