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English Composition 1

Punctuation: Commas

Comma Quiz

Commas are probably the most frequently used punctuation mark, and comma errors come up frequently in student writing.

The most common mistake that students make when using commas is thinking that a comma goes wherever one hears a pause in a sentence. That's not true at all, and this assumption is likely to lead to comma errors. How do you tell where commas go, then? You just need to remember a few simple rules.

There are many situations in which commas are used, but the most common situations are listed below. If you remember all of the rules below, you should be able to use commas correctly most of the time.

(I have used some English teacher jargon on this page, terms such as "restrictive clauses." You certainly don't need to memorize any of the terms, but you should understand and remember all of the principles explained below.)

I. Commas SHOULD be Used in the Following Situations

1) USE COMMAS to Separate Three or More Items in a Series


DO NOT use a comma to separate only two items in a series.


2) USE COMMAS to Offset Introductory Phrases, Transitional Expressions, and Parentheticals


Today, commas are starting to disappear from short introductory phrases, but make sure to use a comma even for a short introductory phrase if the absence of a comma could cause confusion, as in "After eating the dog wanted to go out." Did someone eat a dog? "After eating, the dog wanted to go out" would prevent the reader from getting this first impression.

3) USE COMMAS to Offset Appositives


Note: An "appositive" simply renames something. In the above examples "my best friend" and "Ralph" are exactly the same thing, so you would use commas to offset your "renaming" of the subject. Likewise, "the largest fish in the tank" is an appositive for "a plecostomus," so you need the commas.

4) USE COMMAS to Offset Nonrestrictive Clauses


Note: A "nonrestrictive clause" gives additional information that is not vital to the meaning of a sentence. In both examples above, the information between the commas could be removed, and the main points of the sentences would not change.

5) USE A COMMA Between Two Independent Clauses Separated by One of the "Fan Boys" (for, and, nor, but, or, yet, so)

Note: Errors involving this rule of comma usage are the most common of all comma errors. Remember this one rule, and you most likely can eliminate some comma errors from your writing!

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


In other words, when you have two complete sentences separated by "for," "and," "nor," "but," "or," "yet," or "so," you should place a comma in front of the word that links the two sentences.

Just remember this model:
complete sentence, [fan boys word] complete sentence.

Note: DO NOT use a comma if there is not a new subject after the word (one of the "fan boys") that links the two parts of your sentence.


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

6) USE COMMAS to Separate Independent Clauses from Dependent Clauses

video camera icon Video Comma Usage: Commas and Complex Sentences


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

II. Commas SHOULD NOT Be Used in the Following Situations

1) DO NOT Use Commas for Restrictive Clauses


Note: A "restrictive clause" presents information that "restricts" or limits the meaning of another word. In the first example above, I am not saying that "People make good students" (which would not make much sense); instead, I am "restricting" the kind of people I am talking about—"people who do their work efficiently." Likewise, televisions will not help parents control what their children watch; instead "televisions that contain the new V-chip" will. Because restrictive clauses are vital to the meaning of a sentence, they should NOT be offset with commas.

Note the differences between "nonrestrictive clauses" and "restrictive clauses"!

DO NOT confuse a restrictive clause with an appositive.

Are commas used correctly in the following sentence?

No, they are not. Apparently, the writer is thinking that Hamlet is an appositive for "Shakespeare’s play," that Hamlet and "Shakespeare’s play" and exactly the same thing, but they are not. Shakespeare wrote more than one play, so Hamlet needs to be treated as a restrictive clause (it is "restricting" which play the writer is talking about), and the sentence needs to be rewritten as

Notice the difference in meaning conveyed by the commas alone in the following examples:

In this example, the lack of commas indicates that Big Bubba has more than one "popular song." Commas are not used because "Stuck in the Outhouse Again" is acting as a restrictive clause--it is restricting which "popular song" I am referring to. The title of the song is not simply renaming "popular song."

In this example, the commas indicates that Big Bubba has only one "popular song." Commas are used because "Stuck in the Outhouse Again" is acting as an appositive, an exact renaming of Big Bubba's only "popular song."

Using the same principle, can you tell the difference in meaning between the two sentences below?

There is a big difference!

2) DO NOT Use Commas to Separate a Subject from its Verb


You would never write, "I, am going to the store" or "He, is here," right? The above examples are no different; they just have longer subjects. Even long subject, though, should not be separated from their verbs with commas.

3) DO NOT Use Commas to Separate Two Independent Clauses


Comma Quiz

Using a comma to separate two complete sentences creates a "comma splice." To correct a comma splice, (1) replace the comma with a semicolon, (2) replace the comma with a period, or (3) keep the comma but add a word after the comma that logically "links" the two sentences (one of the "fan boys" would be a good choice).

Notice the third example above. Creating a comma splice with the use of "however" in this way is a common error. The sentence should be written as "The exam was difficult; however, I answered all of the questions correctly!"

Another model you should remember is the following: complete sentence; [however, consequently, therefore], complete sentence.

This page was last updated on July 23, 2008. Copyright Randy Rambo, 2006.