Relative clauses provide extra information about a noun in a sentence. They start with relative pronouns like who, whom, whose, which, and that.

1. Defining Relative Clauses

• Essential information: They define exactly who or what we are talking about.
• No commas are used.
• Relative pronoun “that” can replace “who” or “which” in informal English.

✅ Examples:

• The book that I borrowed was fascinating. (Identifies a specific book)
• The woman who lives next door is a doctor. (Specifies which woman)
• The students whose exams were postponed were relieved.

2. Non-Defining Relative Clauses

• Extra, non-essential information: The sentence still makes sense without it.
• Commas are required.
• “That” is never used in these clauses.

✅ Examples:

• My brother, who lives in Canada, is visiting next month. (Extra info, we already know who my brother is)
• Paris, which is known for its landmarks, attracts millions of tourists.

Key Differences

Feature	Defining Relative Clause	Non-Defining Relative Clause
Essential Information?	Yes	No
Commas Used?	No	Yes
“That” Allowed?	Yes	No
Sentence Makes Sense Without It?	No	Yes

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