Commas

Commas Explained

Guideline 1: Use a comma to separate full sentences linked with FANBOYS.

If you have what can be two separate sentences but want to make them one (creating a compound sentence), use a comma and a FANBOY (for, and, nor, but, or, yet, so) to link them. The comma is placed in front of the coordinating conjunction.

Examples:

• My English Instructor was a good teacher, and she taught me a lot about the writing process.

• We left the house later than we hoped, but we still made it to the concert on time.

Notice how the above sentences can be separated into two different sentences. For instance, the first example could be written like this:

• My English Instructor was a good teacher. She taught me a lot about the writing process.

Note: A comma isn't used with FANBOYS to link words or phrases (it is only used to link full sentences).

Examples:

• I like both English and math.

• Unnecessary comma: I like both English, and math.

• He acted hungry but wasn’t.

• Unnecessary comma: He acted hungry, but wasn’t.

For more on sentence combining with commas and conjunctions, check out our page on Independent and Dependent clauses.

Guideline 2: Use commas after introductory elements.

They're hard to define, but an introductory element begins a sentence by providing a transition from the last sentence or background information. They come in the form of prepositional phrases, subordinate clauses, and transitional expressions. Whenever one of these is used at the beginning of a sentence, a comma can be placed after it.

Examples:

• Prepositional phrase: In a hard fought contest, the home team prevailed after two overtimes.

• Subordinate clause: Because I did well on my final essay, I should be able to pass the class.

• Transitional expression: For example, Aims offers a variety of services that can benefit students.

Guideline 3: Use commas to set off nonessential elements.

A nonessential element is a word or phrase that, if removed from a sentence, doesn't take away from the meaning. Nonessential elements are offset with commas, both before and after.

Examples of nonessential elements:

• I went to the movies with my neighbors, Ron and Sally, and then we went to dinner.

• The students in my morning class, ENG 121, like to participate in the discussions.

• Her best friend, Heather, is planning a surprise party for her birthday.

Guideline 4: Use a comma to separate items in a list or a series.

A series or a list is defined as three or more. Anytime there is a list of three or more items, use a comma to separate them.

Examples:

• I went to the store and bought milk, eggs, bread, and fruit.

• In my American literature class we read The Great Gatsby, All the King’s Men, As I Lay Dying, and the Grapes of Wrath.

Note: There is often confusion about whether or not to place a comma in front of the word and in the last item of a list. It's up to you, but be consistent in your choice.

Guideline 5: Use a comma to introduce a quotation.

Examples:

• On the student’s paper, the instructor wrote, "Your thesis is well constructed but should be moved to the end of the introduction."

• He said to me, "I appreciate your willingness to participate in the classroom discussions."

However, using "that" negates the need for a comma

• On the student’s paper, the instructor wrote that "Your thesis is well constructed but should be moved to the end of the introduction."

• He said to me that "I appreciate your willingness to participate in the classroom discussions."

Guideline 6: Use a comma with addresses, dates, and long numbers.

Place a comma between the street and city, between the city and the state, and at the end of the address.

Examples:

• Aims Community College is located in Greeley, Colorado.

• Use the address 5401 West 20th Street, Greeley, Colorado 80634, for any mail that needs to be sent to Aims Community College.

Place a comma between the day and the year and also after the year.

Examples:

• August 22, 2011, is the day I began my first semester of college.

• The signing of the Declaration of Independence on July 4, 1776, led to the founding of the United States of America.

When using long dates in writing, place a comma every thousandths place, or to separate numbers into groups of three, beginning on the right.

Examples:

• Denver is called the mile high city because it is roughly 5,280 feet above sea level.

• My new position will pay me a salary of $40,000 a year.