No commas to set off restrictive (essential) elements

Restrictive elements are modifiers or appositives that restrict the meaning of the nouns they follow. Because they are essential to the meaning of the sentence, they are not set off with commas.

Example sentence with editing. Original sentence: Skaters, who use performance-enhancing drugs, risk losing any awards they have won. Revised sentence: Skaters who use performance-enhancing drugs risk losing any awards they have won.

The modifier who use performance-enhancing drugs restricts the meaning of Skaters and is therefore essential to the meaning of the sentence. Putting commas around the who clause falsely suggests that all skaters use drugs.

Example sentence with editing. Original sentence: Margaret Mead's book, Coming of Age in Samoa, stirred up considerable controversy when it was published in 1928. Revised sentence: Margaret Mead's book Coming of Age in Samoa stirred up considerable controversy when it was published in 1928.

Since Mead wrote more than one book, the appositive contains information essential to the meaning of the sentence.

Exercise: Misuses of the comma 1

Exercise: Misuses of the comma 2

Related topic:

Nonrestrictive vs. restrictive elements

appositive A noun or noun phrase that renames a nearby noun or pronoun: Bailey, the representative from Alabama, voted for the bill.