Relative Clauses in English Grammar
1. What Is a Relative Clause?
A relative clause is a type of dependent (subordinate) clause that gives more information about a noun. It usually comes after the noun it describes and begins with a relative pronoun such as:
- who
- whom
- whose
- which
- that
- where
- when
Relative clauses help us identify, describe, or give extra information about people, things, places, or times.
Example:
- The man who is wearing a blue jacket is my teacher.
The relative clause “who is wearing a blue jacket” tells us which man we mean.
2. Why We Use Relative Clauses
Relative clauses are used to:
- Avoid repetition
- Make sentences more precise
- Combine ideas into one sentence
Compare:
- I met a woman. She lives next door.
➡ I met a woman who lives next door.
The second sentence is smoother and more natural.
3. Relative Pronouns and Their Uses
Who
Used for people (subject).
- She is the teacher who teaches English.
- I know a boy who plays the piano.
Whom
Used for people (object).
(In modern English, it is often replaced by who or omitted.)
- The woman whom I met yesterday was kind.
- The woman who I met yesterday was kind.
- The woman I met yesterday was kind.
All three are acceptable in modern English.
Whose
Shows possession (people or things).
- The student whose bag was lost is crying.
- I read a book whose cover was red.
Which
Used for things or animals.
- This is the book which I told you about.
- She bought a phone which was very expensive.
That
Used for people or things (very common in spoken English).
- This is the movie that everyone likes.
- She is the girl that won the prize.
Note: That is usually not used in non-defining relative clauses.
Where
Used for places.
- This is the café where we met.
- I remember the park where I played as a child.
When
Used for time.
- I remember the day when we first met.
- That was a time when life was simpler.
4. Defining vs. Non-Defining Relative Clauses
This is one of the most important points.
A. Defining Relative Clauses
Defining relative clauses give essential information. Without them, the meaning is unclear.
- No commas
- That is allowed
- Relative pronoun can sometimes be omitted
Example:
- The student who studies hardest will succeed.
(Which student? The one who studies hardest.)
More examples:
- The book that I bought yesterday is interesting.
- People who exercise regularly live longer.
B. Non-Defining Relative Clauses
Non-defining relative clauses give extra information. The sentence still makes sense without them.
- Use commas
- That is not allowed
- Relative pronoun cannot be omitted
Example:
- My brother, who lives in Osaka, is a teacher.
(You have only one brother; the clause adds extra information.)
More examples:
- This book, which was written in 1920, is famous.
- Japan, where I live, has four seasons.
5. Omitting the Relative Pronoun
In defining relative clauses, the relative pronoun can be omitted if it is the object, not the subject.
Pronoun omitted (object):
- The movie (that) I watched was great.
- The person (who) I met was kind.
Pronoun NOT omitted (subject):
- The movie that was popular won awards. ❌
(Not: The movie was popular won awards.)
6. Prepositions in Relative Clauses
Prepositions can appear in two positions.
Formal style:
- The person to whom I spoke was helpful.
Informal style (more common):
- The person who I spoke to was helpful.
Both are correct, but informal style is much more common in everyday English.
7. Relative Clauses with Quantifiers
Sometimes relative clauses include expressions like all, some, many, most.
- She has many friends, some of whom live abroad.
- I read several books, all of which were interesting.
These are common in written and academic English.
8. Common Mistakes (Especially for ESL Learners)
❌ Repeating the noun
- This is the book which book I bought.
✅ This is the book which I bought.
❌ Using “that” in non-defining clauses
- My car, that is new, is fast. ❌
✅ My car, which is new, is fast.
❌ Forgetting commas
- My father who lives in Tokyo is a doctor. ❌
(Implies you have more than one father.)
✅ My father, who lives in Tokyo, is a doctor.
9. Why Relative Clauses Are Important
Relative clauses are essential because they:
- Make writing more natural
- Help combine ideas smoothly
- Are used frequently in spoken and written English
- Appear often in tests (Eiken, TOEIC, TOEFL, JLPT-style grammar questions)
10. Summary
A relative clause:
- Describes a noun
- Starts with a relative pronoun
- Comes after the noun
- Can be defining or non-defining
Key points to remember:
- Use who/whom/whose for people
- Use which/that for things
- Use commas in non-defining clauses
- You can sometimes omit the pronoun
- That is not used in non-defining clauses
