Commas

The purpose of commas is to make communication clearer. The omission, overuse, or misuse of commas affects clarity, especially in long sentences.

I. Introductory Elements

Use a comma to set off an introductory element and the rest of the sentence. This could be a word or a phrase that introduces the main information in the sentence.

Study these examples.

  1. All day yesterday, my neighbor was playing loud music.
  2. Therefore, one should come to every class.
  3. Although there was no specific attendance requirement, I did poorly in the class because I got too far behind.

II. Coordinating Conjunctions

Use a comma before the coordinating conjunctions "for, and, nor, but, or, yet, so" (easy to remember by the acronym FANBOYS), when they join two independent clauses (they can stand alone as separate complete sentences).

Study these examples.

  1. The professor didn’t have an attendance requirement, but I still should have gone to class regularly.
  2. The professor didn’t have an attendance requirement. I still should have gone to class regularly.
  3. The class was at eight, and I had a hard time getting up that early.
  4. The class was at eight. I had a hard time getting up that early.

Do not use a comma before the coordinating conjunctions "for, and, nor, but, or, yet, so" when they occur in the middle of a sentence that does not include independent clauses.

Study these examples.

  1. I slept in too late and missed my eight o’clock class again.
  2. I should go to class regularly but just can’t get up early.

III. Independent and Dependent Clauses

Use a comma to join an independent and dependent clause.

Study these examples.

  1. Although it is late March, the weather is very cold.
  2. While she was reading her research paper, her friend arrived.

IV. Listed Items

Use commas to separate listed items.

Study these examples.

  1. They bought flowers, books, and paper.
  2. We grow strawberries, cranberries, and blueberries.

V. Additional Information

Use commas to signal some additional information given in the middle or the end of the sentence.

Study these examples.

  1. President John F. Kennedy, who was assassinated in 1963, was an eloquent speaker.
  2. Bill hates his boss, the woman in the corner office.

Practice

Correct the following:

  1. I really enjoy the eggnog lattes at Starbucks every Christmas while my friend prefers the ones at Peet’s.
  2. At the Starbucks drive-through this morning the hungry teenagers ordered a Frappuccino a latte two bagels and three petite vanilla scones.
  3. When students first come to college writing papers is often a big challenge.
  4. The writer has to make an argument, and provide evidence to support the claim.
  5. By improving my science writing ability I can better communicate with scientists.

References

Explanations and some examples are adapted with modifications from the following resources:

Ferris, D. (2014). Language power: Tutorials for writers. Boston: Bedford/St Martin's.