Clauses beginning with question words (e.g. who, which, where) are often used to identify people and things. Clauses used like this are called relative clauses. They can also be called adjective clauses.

Examples are given below.

• James, who is my neighbor, is a well-known painter. (Here the relative clause ‘who is my neighbor’ gives more information about the noun James.)
• This is the house that my grandfather built. (Here the relative clause ‘that my grandfather built’ gives more information about the noun house.)
• I have never met the people who live next door. (Here the relative clause ‘who live next door’ identify the noun people.)
• I know a girl who works in a pub.
• I have found the keys that you were looking for.

Relative pronouns

When words like who, which and that are used to introduce relative clauses, they are often called relative pronouns. Relative pronouns can be the subjects of verbs in relative clauses. Note that who is used to refer to people and which is used to refer to things. That can be used to refer to both people and things.

• Who is that fat woman who sits next to James? (NOT Who is that fat woman which sits next to James?)
• The people that live next door aren’t very sociable. OR The people who live next door aren’t very sociable. (That can refer to both people and things.)
• What happened to those hundred pounds which I lent you? OR What happened to those hundred pounds that I lent you? (Both which and that can refer to things.)

Relative pronouns can also be the objects of verbs in relative clauses. Note that in a formal style, who is not normally used as an object. Instead, we use whom.

• She married someone whom I really admire. (Formal)
• She married someone who I really admire. (Informal)