Commas

Commas before coordinating conjunctions: for, and, nor, but, or, yet, so (FANBOYS)
Test Yourself A

When there are more than two items in a series

When there is more than one adjective in a series
Test Yourself B

After introductory words
Test Yourself C

Around words that are not necessary
Test Yourself D

Other Uses of Commas
Test Yourself E

Rules for Using Commas

There are four basic rules for when to put a comma in a sentence. Just as with any punctuation mark, if there is not a rule to put one somewhere, you shouldn’t. There is no pause rule for commas.

1. Use a comma before the words for, and, nor, but, or, yet, so when they separate two word groups which can stand alone as sentences (independent clauses).These words are conjunctions – words which join parts of a sentence. When they are used to separate two independent clauses, they are called coordinating conjunctions. The acronym FANBOYS is often used to remember these words.

The mother went to the store, but the child went to school.

The mother went to the store is a word group which can stand alone as a sentence (independent clause). The child went to school is a word group which can stand alone as a sentence (independent clause).

Therefore, there should be a comma before the word but.

The mother went to the store but not the child.

There is no comma here because the word group not the child cannot stand alone as a sentence.

2. Using a comma when there are more than two items in a series.

I like apples and bananas.

No comma. There are only two items.

I like apples baked with walnuts and bananas topped with chocolate and whipped cream.

No commas. It does not make any difference if there is more than one word in the item.

I like apples, bananas, and peaches.

There must be a comma before the word and. The standard rule is that when there are more than two items in a series, put a comma after each item except the last item. This is true for when another word such as or is joining the last word.

(Note: Some publications and teachers do not require the use the comma before the and when there are more than two items in a series. However, since many instructors and standardized tests do require the comma, it is safer to put a comma after each item except the last item when there are more than two items in a series.)

2.b. When there is more than one adjective in a series, separate the adjective with a comma if the order can be changed and not be awkward.

Correct:

He had a long, bushy beard.

He had a bushy, long beard.

A comma is required because the adjectives can be switched around.

The juggler used three yellow balls.

Incorrect:

The juggler used yellow three balls.

There should not be a comma since the adjectives cannot be switched around.

3. Use a comma after introductory words (words which introduce a main clause).

After the dance, they went home.

They went home is the main clause.

Because the rain started, she rolled up the windows.

She rolled up the windows is the main clause.

She rolled up the windows because the rain started.

Now the main clause is first; there are no introductory words and, therefore, no comma. Note that there is no rule that says to put a comma before the word because.

(Note: Some publications and instructors say that the comma after introductory words may be dropped if there are only one or two words used to introduce the main idea such as in the following sentence: Today, we will play golf. However, since many instructors require the traditional use, it is safer to put the comma after all introductory words.

4. Use a comma around words that are not necessary to the meaning of the sentence.

She, however, stayed home.

Commas are used because the sentence does not need however to make sense.

He went to the store; however, she stayed home.

Now the however is starting a new sentence, so there must be a semi-colon in front of it and not a comma.

Her sister Catherine went with her.

This indicates the word Catherine is necessary to the meaning, presumably, since she may have other sisters.

Her sister, Catherine, went with her.

Here the word Catherine is incidental and not intended as necessary for the meaning of the sentence. This may indicate that she has only one sister who does not need to be precisely identified by name.

These are the main rules for putting commas in sentences. There are other rules for commas with quotation marks and for standard usages such as 10,000 or January 5, 2007. However, it is easier to remember and apply if we break up the rules as I have done here.

If you are not sure whether to use a comma and there are no quotation marks or standard usages, then ask yourself the following questions:

  • Is there a FANBOYS situation?
  • Is there an items-in-a-series situation?
  • Are there introductory words (words that come before the main idea of the sentence)?
  • Are there unnecessary words (words that are not necessary to the main idea of the sentence)?

If not, don’t put a comma there.

Other Uses of Commas

There are other uses of commas:

To separate a signal phrase (words that say who says the quote)from a quote:
“There will be an earthquake along the Santa Barbara fault within the next ten years,” according to Morelli.
(Note that the comma is before the end quotation mark. When a rule calls for a period or comma to be next to an end quotation mark, the period or comma goes before the end quotation mark.)

Numbers – to separate out thousands: 1,000; 300,000; 1,000,000

Dates – January 12, 2008

Around a larger geographical entity following a location in that larger geographical entity: She lived in Jacksonville, Florida, for a short time.