Relative Pronouns — who, which, that

Relative pronouns introduce relative clauses that give information about a noun. 'Who' refers to people, 'which' to things, and 'that' can refer to both. 'Whom' is the object form of 'who'.

What are Relative Pronouns?

Relative pronouns introduce relative clauses — clauses that add information about a noun.

The boy who won the race is my friend.

The relative clause who won the race tells us which boy.

The Main Relative Pronouns

Pronoun	Used for	Example
who	people (subject)	the woman who* called*
whom	people (object, formal)	the woman whom* I called*
which	things / animals	the book which* I read*
that	people or things (informal)	the dog that* barked*
whose	possession (people or things)	the student whose* bag was lost*

Defining vs. Non-Defining Relative Clauses

Defining (no commas)

The clause is essential — it identifies which person or thing.

The cat that scratched me lives next door. (tells us which cat — essential)

Non-defining (with commas)

The clause gives extra, non-essential information.

My cat, which is 7 years old, loves to sleep. (extra info — remove and sentence still works)

Warning

That is NOT used in non-defining relative clauses. ✗ My cat, that is 7 years old, loves to sleep. ✓ My cat, which is 7 years old, loves to sleep.

Omitting the Relative Pronoun

In defining clauses, you can omit the pronoun when it is the object:

The film (that) I watched was brilliant. (I = subject, that/which = object — can omit) The man who called me was friendly. (who = subject — cannot omit)

Real world: newspaper article

The scientist who discovered the new species works at Oxford University. The research, which was published last week, has already attracted international attention.

Real world: product review

The phone that I bought last month has excellent battery life. The company, whose customer service I contacted, replied within an hour.

Tip Relative pronouns appear in newspapers ("the politician who resigned"), product descriptions ("the laptop that we recommend"), formal writing ("the decision, which was made unanimously"), and everyday speech ("the friend whose car broke down"). They allow you to combine two sentences into one fluent sentence — a key skill in writing.

Practice Problems

Choose: 'The teacher __ explains things clearly is very popular.' (who / which / that)

Show answer

'who' — refers to a person (the teacher). 'that' is also acceptable in informal use.

Add commas if this is non-defining: 'My brother who lives in Paris is visiting us next week.'

Show answer

If you have only one brother: 'My brother, who lives in Paris, is visiting us next week.' (non-defining — commas needed). If there are multiple brothers, no commas (defining).

Can you omit 'which'? 'The book which she lent me was fascinating.'

Show answer

Yes — 'which' is the object here. 'The book she lent me was fascinating.' is correct.