Commas with adjective phrases

Prepositional phrases or verbal phrases (infinitives or participles) may function as adjectives modifying nouns or pronouns.

Nonrestrictive phrases are set off with commas; restrictive phrases are not.

Heading: Nonrestrictive phrase (with commas). Example sentence with editing. Original sentence: The helicopter with its million-candlepower spotlight illuminating the area circled above. Revised sentence: The helicopter, with its million-candlepower spotlight illuminating the area, circled above.

The with phrase is nonessential because its purpose is not to specify which of two or more helicopters is being discussed.

Heading: Nonrestrictive phrase (with commas).Example sentence with editing. Original sentence: The cleft palate among all birth defects is often easily repaired with a series of surgeries. Revised sentence: The cleft palate, among all birth defects, is often easily repaired with a series of surgeries.

The phrase among all birth defects does not change the meaning of the sentence, so it is nonessential and is set off with commas.

Heading: Restrictive phrase (no commas). Example sentence with editing. Original sentence: One corner of the attic was filled with newspapers, dating from the turn of the century. Revised sentence: One corner of the attic was filled with newspapers dating from the turn of the century.

Dating from the turn of the century restricts the meaning of newspapers, so the comma should be omitted.

Exercises:

Major uses of the comma 1

Major uses of the comma 2

All uses of the comma

Related topics:

Commas and restrictive and nonrestrictive elements: Overview

Distinguishing between restrictive and nonrestrictive from context

Commas with adjective clauses

Commas with appositives