Defining & non-defining relative clauses

Upper Intermediate (B2)en

Defining and Non-Defining Relative Clauses: Clarity, Precision, and Extra Information

Relative clauses allow us to give more information about a person, thing, place, or idea without starting a new sentence. The focus is not only on forming relative clauses correctly, but on choosing the correct type to control meaning, emphasis, and tone.

1. What Is a Relative Clause?

A relative clause:

gives additional information about a noun
usually begins with a relative pronoun (who, which, that, whose, where, when)
comes immediately after the noun it describes

Relative clauses are divided into defining and non-defining clauses, and the choice between them affects meaning.

2. Defining Relative Clauses (Essential Information)
Defining relative clauses give essential information. They tell us which person or thing we are talking about. Without this information, the meaning of the sentence would be unclear or incomplete.

Key features:

the information is necessary to identify the noun
no commas are used
that can be used instead of who or which
the relative pronoun can sometimes be omitted

Examples:

“The student who sits next to me speaks four languages.“
“The book that you recommended was very useful.“
“I remember the moment when we first met.“
“The people I spoke to were very helpful.“

3. Non-Defining Relative Clauses (Extra Information)
Non-defining relative clauses give additional, non-essential information. The noun is already clear, and the clause simply adds extra detail.

Key features:

the information is not essential
commas are always used
that cannot be used
the relative pronoun cannot be omitted
more common in formal writing

Examples:

“My brother, who lives in Canada, is visiting next month.“
“The conference, which was held online, attracted thousands of participants.“
“Our teacher, who has a PhD in linguistics, published a new book.“
“The company, whose headquarters are in Berlin, is expanding rapidly.“

4. Meaning Differences: Defining vs Non-Defining
Choosing the wrong type of relative clause can change the meaning of a sentence.

Examples:

“Students who study regularly perform better in exams.“
(Only some students — the clause defines which ones.)
“Students, who study regularly, perform better in exams.“
(All students are described as studying regularly.)
“My colleague who works remotely joined the meeting late.“
(I have more than one colleague.)
“My colleague, who works remotely, joined the meeting late.“
(I have only one colleague.)

No commas = we are choosing

Commas = we are adding

5. Relative Pronouns: Correct Use
Common relative pronouns and their typical uses:

who → people (subject)
whom → people (object, formal)
which → things and ideas
that → people or things (defining clauses only)
whose → possession (people and things)
where → places
when → time expressions

Examples:

“The woman who interviewed me was very professional.“
“The person whom I contacted replied immediately.“
“The system which controls access needs updating.“
“The device that controls the temperature needs to be replaced.“
“The house whose roof was damaged has been repaired.“
“The city where the conference took place is known for its innovation.“
“The year when the law changed was controversial.“

6. Omitting the Relative Pronoun (Defining Clauses Only)
In defining relative clauses, the relative pronoun can be omitted when it is the object, not the subject.

Examples:

“The film Ø I watched last night was disappointing.“
“The advice Ø she gave me helped a lot.“

Pronoun cannot be omitted:

when it is the subject
in non-defining clauses

Examples:

“The teacher who explains everything clearly is very popular.“
“My aunt, who lives abroad, is coming to visit.“

7. Punctuation and Intonation

Defining clauses:
no commas
spoken without pauses
Non-defining clauses:
commas required
spoken with pauses
written like extra information in brackets

Incorrect punctuation can change or confuse meaning.

8. Key Takeaways

Relative clauses add information about a noun.
Defining relative clauses identify which person or thing is meant.
Non-defining relative clauses add extra, non-essential information.
Commas are essential in non-defining clauses.
That is only used in defining relative clauses.
Relative pronouns can only be omitted in defining clauses when they are objects.
Choosing the correct clause type improves clarity, accuracy, and tone.

Related Vocabulary

Expand your vocabulary with words related to this grammar topic