Answer:
Restrictive clauses limit the possible meaning of a preceding subject. ... Nonrestrictive clauses tell you something about a preceding subject, but they do not limit, or restrict, the meaning of that subject.
Step-by-step explanation:
Restrictive: A restrictive clause is essential for meaning. A restrictive clause is not offset with commas. For example: The boy who broke the window is at the door.
Non-restrictive: Nathan, whose sister is my best friend, will be coming on the trip with us. ( Whose sister is my best friend is a nonrestrictive clause. It contains the subject sister and the verb is. The clause modifies the noun Nathan, providing additional, nonessential information about it )