How to Use the Comma: Rule No. 1—Using Commas with Clauses

It's a new year, so I'm inaugurating a new round of blog posting. I'll start by posting some of the helpful writing tips I wrote for the now defunct Suite 101 site a few years ago. First up: the handy but not-so-dandy comma.

The comma: the most used piece of punctuation in the English language but also the most misunderstood.  

Students of writing are often told by well-meaning teachers to put a comma in a sentence wherever they would pause while speaking the sentence. However, this is not very useful advice. Pausing may depend on the individual writer’s preference, and it may also vary from oral communication to written speech.  For example, in the sentence

 Learning to use commas the proper way can only enhance a student’s skills in writing and reading.

some speakers may pause after the word “way.”  Others may pause after “writing.”  Either way is fine; however, no commas are needed in the sentence.

Learning a few simple rules can help students and even more experienced writers communicate more effectively and avoid embarrassing mistakes. We'll start off with the admittedly arbitrary Rule No. 1: Using commas with clauses.

Independent Clauses

A clause is an arrangement of words that conveys an idea. For example, “to go to the store” conveys an idea, although it is not complete. An independent clause contains a complete thought than can be expressed as a sentence: “John went to the store.”

A sentence, by the way, needs two elements: a subject and a verb.  The shortest verse in the Bible—“Jesus wept.”—has both elements and so it is a complete sentence.

On the other hand, a dependent clause needs something to complete it. If we stick the word “After” in front of “John went to the store,” we need another clause—an independent one—to complete the thought:

                        After John went to the store, he made dinner.

Joining Independent Clauses
Use a comma and a coordinating conjunction to join two independent clauses:

                        John went to the store, and he bought milk.

A coordinating conjunction (for, and, nor, but, or, yet and so--FANBOYS, mnemonically) is a short word that clarifies the relationship between elements of a sentence. It helps writers avoid a common error known as a comma splice:

                        John went the the store, he bought milk.

If two clauses can stand alone, they should not be joined together with only a comma. This is just one of those English-language rules that writers have come to accept as true. If you violate this rule--even intentionally--you will look as if you don't know the difference. (And, let's be honest: Don't you feel like your ready to stop the sentence after "store"?)

Notice that you could also put a period or a semicolon in place of the comma, and either would work just fine.

When to Leave Out the Comma

Suppose we want to shorten the sentence:

                        John went to the store and bought milk.

Notice that the comma is removed because the phrase “bought milk” cannot stand on its own.

Test Yourself

Are commas needed in the following sentences?  (Answers appear at the end of the article.)

         a. John went to the store and Mary made dinner.

         b. Abraham Lincoln was the sixteenth president and was assassinated.

         c. George Washington was the first president but he never lived in the White House.

         d.  John Adams came in second in the election so he became the first vice president.

         e.  Adams later became president but served only one term.

Commas help clarify relationships between the elements of a sentence and sometimes (but not always) provide a necessary pause. Knowing when to use a comma—to separate independent clauses, for example—can save you time and embarrassment.  (Answer: commas are needed in sentences a, c, and d.)


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