Meet the comma

Meet the comma

Probably no other mark of punctuation is used—or misused—more than the comma.

Add to that a slight variance between British and American punctuation, and we have even more confusion.

Once upon a time about 50 to 150 years ago, writing in English was much heavier than it is today. Long sentences were considered a mark of careful writing. Henry David Thoreau, for example, who championed the cause of simplicity was most eloquent when he framed his thoughts in delicious, long sentences. For example…

“On either hand, and beyond, was a wholly uninhabited wilderness, stretching to Canada. Neither horse nor cow, nor vehicle of any kind, had ever passed over this ground; the cattle, and the few bulky articles which the loggers use, being got up in the winter on the ice, and down again before it breaks up.”—Ktaadn, Part II.

Eight commas and 54 words in two sentences. Not one misplaced, not one incorrectly used. Excellent writing. But times are changing. In today’s mad rush we like our sentences even shorter than this example—and more directly to the point.

Still, we occasionally need a short pause or a break, and for that we have the comma.

The general rule about commas is to use them when you need to separate words, phrases, or other constructions from each other.


Always in a sentence with a list of three or more items, you need to separate the items with commas.

Example: My favorite vegetables are spinach, carrots, and potatoes.

The comma before “and” in the list above is sometimes called a “serial comma.” It is not used as rigorously in American writing as it is in British writing.

Following introductory words or phrases

Example: For the last time, stop interrupting me or I’m going to scream.

You don’t need to place a comma after every phrase that begins a sentence. For example..

On the way home I noticed dark clouds forming on the western horizon.
On the way home, I noticed dark clouds forming on the western horizon.

If the tone of the writing is eager, fast-paced, or moving readily into the future, the comma that slows us down isn’t needed. If the writer wants everyone to slow down just a bit at that point, a comma will do the job.

In general, the rule is…

Commas are usually not needed after an uncomplicated, introductory prepositional phrase:

Beneath the surface I saw my gold watch…
After lunch we drove to the gym.
In my pocket I found a dollar bill.

The rule is, “When in doubt, leave it out.” If you don’t have to slow things down, don’t!

Transitional words such as “however” or “therefore” that are abundant in writing of the early twentieth century usually, but not always, need to be set apart by commas. Examples:

No oxygen was present. Therefore, the chemical reaction did not occur.

I went over the key points five times with Steve. However, he didn’t pay any attention and
missed all of the questions on the final exam.

Sometimes “however” has the function of describing an adverb, and that means no comma is needed. For example…

However hard he tried, Thomas could not uncouple the trailer from the car.

In short structures, “therefore” doesn’t need the slowdown of one or more commas. Example…

I am therefore going to forget this ever happened.

Commas are subject to personal judgment as much as to rules of grammar. Take this short quiz: