Restrictive and Nonrestrictive Elements

RESTRICTIVE ELEMENTS

Restrictive elements are word groups that are necessary to retain meaning. They are not set off from the rest of the sentence by commas or other punctuation.

INCORRECT: William Faulkner's novel, Light in August, is my favorite book.

CORRECTED: William Faulkner's novel Light in August is my favorite book.

Because Faulkner has written numerous novels, the writer must specify which one of them he's referring to. Setting the title off with commas would suggest that it could be removed without changing the meaning of the sentence; however, the title is essential for meaning.

For the same reason, restrictive clauses are not set off from the rest of the sentence by commas or other punctuation. These clauses usually begin with that or who.

INCORRECT: To do yoga, I need a shirt, that is loose and comfortable.

CORRECTED: To do yoga, I need a shirt that is loose and comfortable.

In this example, the speaker does not need just any shirt. It must be loose and comfortable. Because the phrase changes the meaning of the word "shirt," the phrase is restrictive. Removing it would change the meaning of the sentence.

NONRESTRICTIVE ELEMENTS

Nonrestrictive elements are groups of words that can be removed without changing the meaning of the sentence. Because removing them does not change meaning, nonrestrictive elements can be set off from the rest of the sentence.

CORRECT: I'd like to have more pets, but I only have one cat, Bill.

Because the writer only has one cat, its name just adds extra information. If the name were removed, the reader would still know what cat was being discussed.

For the same reason, nonrestrictive clauses can be set off from the rest of the sentence by commas or other punctuation. These clauses usually begin with which or who.

CORRECT: When I do yoga, I wear my favorite shirt, which is really old.

In this example, the fact that the writer's favorite shirt is old has no bearing on the meaning of the word shirt. It's simply a detail she decided to add. Therefore, it is nonrestrictive. It can be removed without changing the meaning of the sentence.