Restrictive and Non-Restrictive Clauses

A clause is a part of a sentence. A relative clause is usually introduced by a relative pronoun (who, which, that, when, where, or whose).

Relative clauses are often used to define or to add information to nouns and pronouns

When a relative clause is used to define what we are talking about, no commas are used. This type of clause is known as defining relative clause or restrictive relative clause.

Non-defining or non-restrictive relative clauses are used to add extra information or make a comment on something or somebody. They do not help define what or who we are talking about.

One or two commas areused in non-defining or non-restrictive relative clauses.