What is a relative clause in English?

A relative clause is a part of a sentence that gives more information about a noun. It starts with a relative pronoun like who, which, that, or whose. For example: 'The woman who lives next door is a doctor.' The clause 'who lives next door' tells us which woman.

What is the difference between defining and non-defining relative clauses?

A defining relative clause is essential to identify the noun. Without it, the sentence loses meaning. 'The students who passed the exam are happy' (only those students). A non-defining relative clause adds extra information and uses commas. 'My brother, who lives in London, is an engineer' (I have one brother). Non-defining clauses cannot use 'that.'

When do I use 'that' vs 'which' in relative clauses?

Use 'that' in defining relative clauses (no commas) for things and animals. Use 'which' in non-defining relative clauses (with commas) for things and animals. Example: 'The book that I bought is great' (defining, tells which book). 'My new book, which I bought yesterday, is great' (non-defining, extra information). 'That' cannot start a non-defining clause.

Can I leave out the relative pronoun?

Yes, when the relative pronoun is the object of the clause. 'The film that I watched was good' can become 'The film I watched was good' (object of 'watched'). You cannot leave it out when it is the subject: 'The man who called you is here' cannot become 'The man called you is here' because 'man' is the subject of 'called.'

How do I use whose and whom in relative clauses?

Use 'whose' to show possession for people and things. 'The student whose phone rang was embarrassed.' Use 'whom' as the object of a clause for people in formal English. 'The woman whom you met is my aunt.' In everyday English, most people use 'who' instead of 'whom' or omit it entirely.

What relative pronouns can I use for places and time?

Use 'where' for places: 'The restaurant where we had dinner was excellent.' Use 'when' for time: 'Remember the day when we first met?' Use 'why' for reasons: 'The reason why I called is simple.' These are called relative adverbs and they replace a preposition + relative pronoun combination.

Relative Clauses: Rules, Examples and Exercises

Grammar Guide - Updated June 2026

Master relative clauses in English with clear rules, pronoun guides, defining vs non-defining differences, example sentences, and practice exercises for B1-B2 learners.

What Are Relative Clauses?

A relative clause is a part of a sentence that gives more information about a noun. It starts with a relative pronoun such as who, which, that, whose, or a relative adverb such as where or when.

Example: The woman who lives next door is a doctor.

The part in green is the relative clause. It tells us which woman we are talking about.

Relative clauses help you combine two short sentences into one longer, more natural sentence. Instead of saying "I have a friend. She lives in Tokyo," you can say "I have a friend who lives in Tokyo."

Relative Pronouns Guide

Choose the right relative pronoun based on whether you are talking about a person, a thing, a place, or time.

Pronoun	Used For	Example
who	people (subject)	The teacher who* helped me was kind.*
whom	people (object, formal)	The woman whom* you met is my boss.*
which	things and animals	The book, which* I finished yesterday, was great.*
that	people or things (defining only)	The movie that* won the award is excellent.*
whose	possession (people and things)	The student whose* bag was stolen is upset.*
where	places	The park where* we met is beautiful.*
when	time	I remember the day when* we first met.*
why	reasons	This is the reason why* I called.*

Defining vs Non-Defining Relative Clauses

This is the most important difference to understand. A defining clause identifies which noun you mean. A non-defining clause adds extra information.

Feature	Defining Clause	Non-Defining Clause
Purpose	Essential to identify the noun	Extra information, not essential
Commas	No commas	Commas around the clause
Can use that	Yes	No
Can omit pronoun	Yes (when object)	No
Example	The students who passed* are happy.*	The students, who passed, are happy.

Defining Clause

The students who passed the exam are celebrating.

This means only the students who passed are celebrating. Without the clause, the sentence loses its meaning.

Non-Defining Clause

The students, who passed the exam, are celebrating.

This means all the students passed and all are celebrating. The clause adds extra information.

That vs Which: When to Use Each

This is one of the most common questions learners have. Use that in defining clauses and which in non-defining clauses.

Use that in defining clauses (no commas)

The car that is parked outside is mine.

I need a phone that has a good camera.

Use which in non-defining clauses (with commas)

My car, which is parked outside, is five years old.

This phone, which I bought last week, is excellent.

Quick tip: If you see commas around the clause, use which. If there are no commas, use that for things.

When You Can Omit the Relative Pronoun

In defining relative clauses, you can leave out the relative pronoun when it is the object of the clause.

Role	With Pronoun	Without Pronoun
Pronoun is OBJECT	The film that* I watched was great.*	The film I watched was great.
Pronoun is OBJECT	The woman who* I met is kind.*	The woman I met is kind.
Pronoun is SUBJECT	The man who* called is here.*	Cannot omit
Pronoun is SUBJECT	The dog that* barked woke me.*	Cannot omit

Prepositions in Relative Clauses

In formal English, prepositions come before the relative pronoun. In informal English, they stay at the end of the clause.

Style	Formal	Informal / Spoken
People	The person to whom* I spoke...*	The person who* I spoke to...*
Things	The topic about which* we talked...*	The topic that* we talked about...*
Places	The city in which* I was born...*	The city where* I was born...*

Common Mistakes with Relative Clauses

The book who I bought is great.

The book that / which I bought is great. (Use that/which for things)

My mother, that lives in Paris, is a teacher.

My mother, who lives in Paris, is a teacher. (Never that in non-defining)

The man which called you is waiting.

The man who called you is waiting. (Use who for people)

I have a friend he lives in Canada.

I have a friend who lives in Canada. (Use a relative pronoun)

The house who is on the corner is for sale.

The house that / which is on the corner is for sale.

Practice Exercises

Exercise 1: Choose the correct relative pronoun

The woman ___ lives next door is a nurse. (who / which)
I have a car ___ was made in Japan. (who / that)
The student ___ phone rang was embarrassed. (who / whose)
This is the park ___ we first met. (where / who)
The reason ___ I am late is simple. (why / where)

Exercise 2: Defining or Non-Defining? Add commas where needed.

My sister who lives in London is a doctor.
The students who passed the exam are celebrating.
My car which is ten years old still runs well.
People who smoke should quit.
London which is the capital of England has great museums.

Exercise 3: Combine using a relative clause

I have a friend. She speaks three languages.
I bought a phone. It has a great camera.
That is the man. His car was stolen.
We visited a museum. It was very interesting.
I remember the day. We first met on that day.

Answers

Exercise 1: 1. who, 2. that, 3. whose, 4. where, 5. why

Exercise 2: 1. Commas needed (one sister). 2. No commas. 3. Commas needed. 4. No commas. 5. Commas needed.

Exercise 3: 1. I have a friend who speaks three languages. 2. I bought a phone that has a great camera. 3. That is the man whose car was stolen. 4. We visited a museum that was very interesting. 5. I remember the day when we first met.

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Relative Clauses: Rules, Examples and Exercises

What Are Relative Clauses?

Relative Pronouns Guide

Defining vs Non-Defining Relative Clauses

That vs Which: When to Use Each

When You Can Omit the Relative Pronoun

Prepositions in Relative Clauses

Common Mistakes with Relative Clauses

Practice Exercises

Related Grammar Guides

Passive Voice

Countable and Uncountable Nouns

Comparative and Superlative Adjectives

All Grammar Guides

Free Guide: 10 AI Tools to Master English

What Are Relative Clauses?

Relative Pronouns Guide

Defining vs Non-Defining Relative Clauses

That vs Which: When to Use Each

When You Can Omit the Relative Pronoun

Prepositions in Relative Clauses

Common Mistakes with Relative Clauses

Practice Exercises

Related Grammar Guides

Passive Voice

Countable and Uncountable Nouns

Comparative and Superlative Adjectives

All Grammar Guides

Free Guide: 10 AI Tools to Master English

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