Relative pronouns

 A relative pronoun is a pronoun that’s used to introduce a relative clause. The main English relative pronouns are which, that, who, and whom. These words can also function as other parts of speech—they aren’t exclusively used as relative pronouns.

A relative clause introduces further information about the preceding noun or noun phrase, either helping to identify what it refers to (in a restrictive clause) or just providing extra details (in a nonrestrictive clause).

The relative clause comes after a noun or noun phrase (called the antecedent) and gives some additional information about the thing or person in question. The relative pronoun represents the antecedent.