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English Composition 1

Four Comma Rules

This page explains four rules for comma usage that should help you use commas correctly. There are many rules for comma usage, but if you remember just these four rules, you should be on your way toward becoming a master of the comma.

1. The FAN BOYS" Rule

If you have two independent clauses (basically complete sentences) separated from one another with a coordinating conjunction, then you should use a comma in front of the conjunction. You can easily remember the coordinating conjunctions if you remember the words "FAN BOYS." Together, the first letter of each of the conjunctions spells "FAN BOYS." The coordinating conjunctions are for, and, nor, but, or, yet, so. A complete sentence followed by one of these words and another complete sentence means that you should put a comma in front of the conjunction.

video camera icon Video Comma Usage: The "FAN BOYS" Rule.

Remembering and applying the "FAN BOYS" rule can go far in helping you use commas correctly.

video camera icon Watch the "Writing Matters" video presentation on Comma Usage: The "FAN BOYS" Rule.

2. Restrictive and Nonrestrictive Clauses

Clauses often begin with "who" or "which." If the "who" or "which" clause identifies (or restricts) which ones you are talking about, then you do not use commas. If the "who" or "which" clause is just giving extra information and is not identifying or restricting which ones you are talking about, then you should put commas around the phrase.   

3. Appositives

An "appositive" is an exact renaming. When you present an appositive (in other words, when you repeat something but use a different name for it), then you put commas around the appositive. 

4. Commas with Complex Sentences

A complex sentence is made up of an independent clause and one or more dependent clauses. An independent clause can stand alone as a complete sentence; a dependent clause cannot stand alone as a complete sentence. 

video camera icon Video Comma Usage: Commas and Complex Sentences

Dependent clauses--the ones that cannot stand alone as complete sentences--begin with words called "subordinating conjunctions." Below are some of the most common subordinating conjunctions:

If the dependent clause appears before the independent clause, then a comma is used to separate the two clauses, as in the following:

  1. Because Mary and Samantha arrived at the bus station before noon, I did not see them at the station.
  2. While he waited at the train station, Joe realized that the train was late.
  3. After they left on the bus, Mary and Samantha realized that Joe was waiting at the train station.

If the dependent clause appears after the independent clause, then a comma is not used to separate the two clauses, as in the following:

  1. I did not see them at the station because Mary and Samantha arrived at the bus station before noon.
  2. Joe realized that the train was late while he waited at the train station.
  3. Mary and Samantha realized that Joe was waiting at the train station after they left on the bus.

The dependent clauses in the sentences above are italicized. Notice how the two sets of sentences above are identical except for the order of the dependent and independent clauses in the sentences: this order determines the comma usage.

video camera icon Watch the "Writing Matters" video presentation on Comma Usage: Commas and Complex Sentences.

Try this One

In some cases, comma usage can make a big difference in the meaning that you convey. Applying the rules for appositives, restrictive clauses, and nonrestrictive clauses, see if you can tell the difference in meaning between the two sentences below:

There is a big difference in meaning here! And we have to feel sorry for the writer of the second sentence above.

This page was last updated on June 06, 2013. Copyright Randy Rambo, 2007.