Comma Usage Rules: Commas With Nonessential Clauses and Phrases

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The Basics

The fourth rule of comma use is that nonessential elements should be surrounded by commas. But how can you tell the difference between essential and nonessential elements? If you’re not sure, try removing the group of words or change its location in the sentence. If the meaning of the sentence changes, the group of words is essential. If it doesn’t, the group of words is nonessential.

Who and Whom

Phrases and clauses that begin with “who” or “whom” are excellent examples of essential and nonessential clauses. Take a look at the following sentence:

  • The boy who was wearing the green shirt won the race.

If you would remove the clause “who was wearing the green shirt,” the sentence would read “The boy won the race.” Although that would still be a sentence, it wouldn’t mean the same thing. Which boy won the race? The clause “who was wearing the green shirt” would be essential to understanding the meaning of the sentence. On the other hand, take a look at this sentence:

  • The boy in the green shirt, who had just won the race, threw his hands in the air.

In this case, “who had just won the race” is nonessential. Removing the clause would leave “The boy in the green shirt threw his hands in the air.” The clause just provides extra information about the boy – the fact that he had just won the race.


Most appositives are nonessential and should be set off by commas. An appositive is a phrase that renames a noun or pronoun. For example, in the following sentences, “Roberta” and “the lady with the British accent” are appositives:

  • My wife, Roberta, is a successful accountant.
  • Ms. Kelly, the lady with the British accent, teaches gym at the local high school.

In these examples, you could say “My wife is a successful accountant” or “Ms. Kelly teaches gym at a local high school” and the meaning of the sentence would not change. However, there are some appositives that should not be surrounded by commas. These appositives are essential to understanding the sentence. For example:

  • Former Secretary of State Colin Powell took a strong stand on that issue.

Other Nonessential Elements

Here are some examples of other types of nonessential phrases and clauses. Remember, to find out if a clause or phrase is nonessential, try leaving it out of the sentence.

  • The couple, trying desperately to make ends meet, stopped eating out.
  • Carly, of course, refused to come with us.
  • I beg you, Patricia, don’t deny me this one request.

This post is part of the series: When to Use Commas: A List of Comma Rules

Confused by commas? These rules for comma usage will teach you how and when to use commas. Includes information about items in a series, introductory phrases, and comma splices.

  1. Using Commas in a Series: Basic Rules
  2. Using Commas Between Independent Clauses
  3. Using Commas After Introductory Elements
  4. Using Commas With Non-Essential Elements
  5. Miscellaneous Rules of Comma Usage