A pronoun that relates a previous
noun to another clause is called a relative pronoun. The most commonly used
relative pronouns are who, whom, whoever, whomever, whose, that, which, and
what.
The job of a relative pronoun
is to introduce a phrase or clause that adds information to the main idea.
For example:
She
is the girl who won the debate.
Show me the phone that you got for your birthday.
Here is the book, which I will give to my brother for Thanksgiving.
In
the above sentences, “who”, “that”, and “which” are relative pronouns.
In
the first example, the relative pronoun "who" is connecting the previous
noun "girl" to the phrase "won the debate." The relative
pronoun is helping the reader understand that the girl won the debate.