Comma Examples & Explanations

Here are examples of how the comma rules apply, including more detailed explanations. You can click on the highlighted terms to see their definitions.


Rule No. 1: In a simple series, use a comma to separate the elements, but don’t put a comma before the conjunction.

The flag is red, white and blue.

This series is made up of three adjectives: red, white and blue.

He would nominate Tom, Dick or Harry.

This series is made up of three proper nouns: Tom, Dick and Harry.

In both cases, there is a comma separating the first two items, but there is no comma before the conjunction. The lack of a comma before the conjunction is the biggest difference between AP style rules on commas and standard English grammar.

Also note that our rule refers to a “simple” series. In more complex constructions, commas are used before the conjunction.

The most common example of this exception is when a conjunction is used within the items in a series.

I had ham and eggs, toast, and orange juice for breakfast.

This series is made up of nouns: ham and eggs, orange juice, and toast. The comma appears after toast and before the conjunction and that links the three items in this series.



Rule No. 2: Use a comma to separate two independent clauses connected by a coordinating conjunction.

An independent clause is a group of words that could stand alone as a sentence because it has a subject and a predicate. Here are two examples:

The student opened her book. Then she read the chapter.

You could combine them with the coordinating conjunction and:

The student opened her book, and then she read the chapter.

Contrast this with a sentence where the subject occurs only once:

The student opened her book and then read the chapter.

There's no comma here—because now there is only a single clause. A rule of thumb is to check to see if there is a subject explicitly stated with each verb. If two or more verbs go with the same subject, you don't need a comma because you don't have multiple independent clauses.

Here are two more contrasting examples, first a pair of independent clauses joined by a comma:

We are visiting Washington, and we also plan a side trip to Baltimore.

The same thought can be expressed as a single clause without a comma:

We are visiting Washington and also plan a side trip to Baltimore.


Rule No. 3: Use a comma following an introductory phrase of four words or more.

The AP Stylebook isn't this precise, but counting the number of words in an introductory phrase or clause is a good way to eliminate ambiguity about whether you should use a comma a not.

Here's a sentence with a long (more than four words) introductory clause:

When he had tired of the mad pace of New York, he moved to Dubuque.

Here's one with a short introduction (and no comma):

During the night he heard many noises.


Rule No. 4: Use commas to set off modifiers that are not essential to the reader's ability to identify a particular person, place or thing.

The logic here is that if a modifier is not crucial for a reader's understanding it can recede into the background by being set off with commas. If the modifier is essential for the reader to identify who or what is being described, then it should be as close as possible to what it is modifying.

This is an example of a sentence with a nonessential modifier:

The starting quarterback, who drank too much on Saturday night, did not play well on Sunday afternoon.

Since there is only one starting quarterback, the information about his drinking is not essential to identifying him. Contrast that with a sentence like this:

The violinist who doesn't work hard in practice doesn't get a chance to solo.

In the second example, there are many violinists. But the information about practice habits is essential for the reader to understand which one would not get a chance for a solo.

Confusion can arise when a descriptive term appears to be a nonessential modifier. The distinguishing clue usually is the lack of an article or possessive pronoun, which tells you that you have a descriptive term as opposed to a nonessential modifier.

The following sentence is punctuated correctly because the name is not essential to the reader's understanding:

The company chairman, Henry Ford II, made the announcement.

But this sentence is also punctuated correctly because the words "Company Chairman" form a descriptive phrase rather than a nonessential modifier:

Company Chairman Henry Ford II made the announcement.

Right: Julie and husband Jeff went shopping.

Wrong: Julie and husband, Jeff, went shopping.

Right: Julie and her husband, Jeff, went shopping.

Wrong: Julie and her husband Jeff went shopping.

This last sentence would be punctuated properly only if Julie had multiple husbands and the reader needed to know it was husband Jeff (and not, say, husband Joe) who went shopping.


Rule No. 5: Use commas to separate adjectives of equal rank.

If a the word and could be placed between two adjectives without changing the meaning of the sentence, then the adjectives are considered to be equal. Here is an example:

She spoke in a thoughtful, precise manner.

One could say

She spoke in a thoughtful and precise manner.

without changing the sense. Contrast this punctuation with the following:

She wore a cheap fur coat.

Here it would make no sense to say

She wore a cheap and fur coat.

The adjectives in this example are not considered equal because fur is an intergral part of a noun phrase (fur coat) and cheap modifies that entire noun phrase.


Rule No. 6: Use commas to set off words that add emphasis, shift attention or provide a fuller explanation (parentheticals, "yes," "no," names in direct address).

Here are some examples:

It was, after all, only a game.

Yes, I will be there.

The textbook was wrong, too.

Jane, it's time to go.

Put me in, coach. I'm ready to play.


Rule No. 7: Use commas to set off participial modifiers that come at the beginning of a sentence or after the verb.

This sentence includes a present participle, running.

Running down the street, the student stumbled and fell.

In this sentence the past participle pleased modifies the subject, politician.

Pleased by the way things turned out, the politician smiled.

Here a present participle has been formed by adding ing to include.

The material from the entire semester will be on the final, including commas.

A past participle modifies the subject of this sentence.

The student read in silence, amazed by the skill of the novelist.


Rule No. 8: Use a comma, carefully, to set off quotes or paraphrases.

This rule can be a little tricky because it depends on where the quote or paraphrase falls and whether it's a complete sentence or not.

If the quote or paraphrase comes before the attribution, then the application of the rule is straightforward. You simply put the comma between the quote or paraphrase and the attribution.

Here's a direct quote:

"That's simple," the student said. Note very carefully that the comma always, always, always goes inside the quotation mark.

And here's a paraphrase:

The budget crisis may get worse, officials said Monday.

Things get a little trickier if the quoted material comes after the attribution. If there's a direct quote, a comma is used only if a complete sentence is quoted.

The student said, "That's simple."

In the following example, the quote is not a complete sentence and so no comma is used.

The student said the test was "simple."

If there's no quote at all and just a paraphrase, then no comma is used.

The student said he did well on the test because it was so easy.

If the quote consists of two or more sentences, then a colon is used instead of the comma.

The president said: "I plan to run again. Please vote for me."


Rule No. 9: Use a comma with hometowns, ages, names of states and nations used with city names, affiliations, and most large numbers.

This is a pretty easy rule to apply. The trick is to remember that in most of these cases, commas work like parentheses and should be used in pairs.

His journey will take him from Dublin, Ireland, to Fargo, N.D., and back.

The Selma, Ala., group saw the governor.

Nov. 7, 1955, was her date of birth.

The girl, 15, was in high school.

Daniel Moynihan, Ph.D., spoke.

Use a comma for most figures greater than 999. AP lists exceptions for addresses, broadcast frequencies, room numbers, serial numbers, telephone numbers and years.


Rule No. 10: Use a comma to separate duplicate words to eliminate confusion.

What the problem is, is not clear.

As Bill Clinton once said, it all depends on what your definition of is, is.