Understanding Relative Clauses Pt. 2 (defining and non-defining)

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You know your who, which and that. Now let's tackle one of the trickiest parts of relative clauses — the difference between defining and non-defining clauses — plus whose, where, when, and when you can drop the pronoun altogether.

Defining vs. Non-Defining Relative Clauses

This is a crucial distinction!

Defining Relative Clauses (Essential Information)

The relative clause is ESSENTIAL to identify which person or thing we're talking about. Without it, the sentence loses its meaning. No commas.

The woman who lives next door is a doctor. (which woman? the one who lives next door)
Students who work hard succeed. (which students? the ones who work hard)
The car that I bought is red. (which car? the one I bought)

Remove the clause and the meaning falls apart: "The woman is a doctor" — which woman? We don't know.

Non-Defining Relative Clauses (Extra Information)

The relative clause adds EXTRA information but is not essential. The sentence is already clear without it. Use commas — this is very important!

My sister, who lives in Paris, is a doctor. (I have one sister — just adding extra info)
The Eiffel Tower, which was built in 1889, is in Paris. (we know which tower — extra info)
John, who speaks five languages, got the job. (we know who John is — extra info)

Key Differences at a Glance

Feature	Defining	Non-Defining
Commas	NO	YES (essential!)
Essential?	Yes	No (extra info)
Can use "that"?	Yes	No — never!
Can omit pronoun?	Sometimes (object)	Never

Compare these two:

Defining: My brother who lives in London is a doctor. (I have more than one brother — specifying which one)
Non-defining: My brother, who lives in London, is a doctor. (I have one brother — just extra info)

One comma changes the whole meaning!

Remember: "That" can never be used in non-defining clauses:

❌ My sister, that lives in Paris, is a doctor.
✅ My sister, who lives in Paris, is a doctor.

When You Can Omit the Relative Pronoun

Good news — you don't always have to say it! When the relative pronoun is the object of the clause, you can leave it out (in defining clauses only).

Object = Can Omit ✅

The book that I bought is interesting. → The book I bought is interesting. ✅
The woman who I met was very nice. → The woman I met was very nice. ✅
The car which you saw is mine. → The car you saw is mine. ✅

Subject = Cannot Omit ❌

When the relative pronoun is the subject, you MUST keep it:

The book that is on the table is mine. ✅ (must keep)
❌ The book is on the table is mine. (wrong!)

How to tell the difference:

Subject: relative pronoun + verb → who broke, which is, that crashed
Object: relative pronoun + subject + verb → who I met, which you saw, that he bought

WHOSE, WHERE & WHEN

WHOSE — For Possession

"Whose" shows possession — think of it like "his," "her," or "its" inside a relative clause.

The man whose car was stolen called the police. (= his car was stolen)
I know a woman whose daughter is a famous actress. (= her daughter)
The company whose products we use is very successful. (= its products)

Pattern: whose + noun (always)

WHERE — For Places

"Where" is used for places and replaces a preposition + which/that.

The hotel where we stayed was excellent. (= the hotel that we stayed at)
This is the restaurant where we first met. (= the restaurant that we first met in)
The city where I was born is very small.

WHEN — For Times

"When" is used for times. In modern English, it's often omitted or replaced with "that."

Do you remember the day when we first met?
2020 was the year when everything changed.
The day when we met = The day that we met = The day we met ✅ (all fine!)

Quick Reference: whose, where, when + omitting pronouns

Pronoun	Use for	Example
whose	Possession	The man whose car was stolen...
where	Places	The hotel where we stayed...
when	Times (often omittable)	The day when we met...
(omit)	Object in defining clause	The book __ I bought... ✅

Practice

Add commas if needed:

My brother who lives in Berlin is a doctor. [I have one brother]
Students who study hard usually succeed. [which students? — defining]
The Eiffel Tower which was built in 1889 is in Paris. [famous landmark — we know which one]

Can you omit the relative pronoun?

The movie that we watched was good. → _______
The man who lives here is my friend. → _______

Choose whose, where, or when:

The hotel _______ we stayed was excellent.
Do you remember the day _______ we first met?
The man _______ car was stolen called the police.

Answers

My brother, who lives in Berlin, is a doctor. (commas needed)
Students who study hard usually succeed. (no commas — defining)
The Eiffel Tower, which was built in 1889, is in Paris.
Yes — The movie we watched was good. ✅
No — "who lives here" is the subject, must keep it.
where
when
whose

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