Appositives. An appositive is a noun or noun phrase that renames a nearby noun. When an appositive is not essential to identify what it renames, it is set off with commas.

NONRESTRICTIVE APPOSITIVES

Savion Glover’s name identifies him; the appositive the award-winning dancer provides extra information.

RESTRICTIVE APPOSITIVES

The phrase is restrictive because Mozart wrote more than one opera. Therefore, it is not set off with commas.