A relative clause often describes or identifies a noun. In The jacket that has a broken zipper is mine, the relative clause tells readers which jacket is mine.
Defining and supplementary relative clauses
- Defining. The hikers who brought headlamps led the group. The clause selects the hikers with headlamps. It takes no commas.
- Supplementary. Mara, who brought a headlamp, led the group. The name already identifies Mara. The commas set off the extra detail.
When you can leave out the relative word
In a defining clause, you can often omit a relative word that functions as the object. The jacket that I borrowed fits can become The jacket I borrowed fits. Keep the word when it functions as the subject, as that does in that has a broken zipper. Supplementary clauses keep their relative word, as who does in the example with Mara.
Relative clauses are one kind of subordinate clause.
