We use non-defining relative clauses to provide extra information about someone or something. This is not necessary information, meaning that we don't need it to understand who or what is being referred to.
Example
Explanation
Cindy, who I work with, invited us to the party tomorrow.
This is a non-defining relative clause, as providing someone's name is usually enough to identify a person.
Rule 1: We always use a relative pronoun (who, which, whose, or whom) to introduce a non-defining relative clause.
Example
Explanation
At our weekly meeting, which is held every Tuesday, we discussed the launch of a new project.
We use a non-defining relative clause (which is held every Tuesday) to provide extra information which doesn't affect the main idea of the sentence.
Rule 2: In contrast to defining relative clauses, we don’t use that to introduce a non-defining relative clause.
| Mary, that we met at the party, was the only nice person there. | INCORRECT |
| Mary, who we met at the party, was the only nice person there. | CORRECT |
| Mary, that we met at the party, was the only nice person there. | INCORRECT |
| Mary, who we met at the party, was the only nice person there. | CORRECT |
Note: In writing, we use commas around non-defining relative clauses. In speaking, we often pause at the beginning and end of the clause.
Example
Explanation
His mother, who lives in Australia, has a big and fruitful farm.
The non-defining relative clause (who lives in Australia) is separated by commas in writing.
Quiz
1/4
Choose the right relative pronoun to introduce a non-defining relative clause. Yesterday I met Lucy, ___ mother lives in Bristol.
0
correct answers.