Defining and non-defining relative clauses
A clause which clearly defines the antecedent is known as a defining relative clause. (The antecedent is the noun that the relative pronoun refers to.) On the other hand, a clause which merely gives additional information about the antecedent is known as a non-defining relative clause.
Examples of defining relative clauses are:
- Charles Dickens is a writer whom the whole world admires.
- The book which you gave me is very interesting.
- The diamond necklace which I bought for my wife was very expensive.
Examples of non-defining relative clauses are:
- My brother, who lives in Canada, is an accomplished painter.
- Raj, who is my friend, is a handsome guy.
The relative pronoun introducing a defining relative clause can be omitted in an informal style.
- The diamond necklace I bought for my wife was very expensive.
The relative pronoun introducing a non-defining relative clause cannot be omitted.
- Maria, who babysits my kids, is my aunt’s daughter. (NOT Maria, babysits my kids, is my aunt’s daughter.)
The relative pronoun cannot be omitted in a non-defining relative clause.
If the non-defining relative clause occurs in the middle of the sentence, it must be preceded and followed by a comma.
- My son, who makes models from clay, has won many prices.
This use of the comma often distinguishes between defining and non-defining relative clauses.