Relative Clauses
Understanding Defining vs. Non-defining Relative Clauses
What Are Relative Clauses?
Relative clauses are parts of a sentence that give us more information about a noun. They begin with relative pronouns like who, which, that, whose, where, or when. Understanding the two types of relative clauses is essential for clear and effective communication.
Defining Relative Clauses
Defining relative clauses (also called restrictive clauses) provide essential information about the noun they modify. Without this information, the sentence would be unclear or incomplete.
• No commas are used
• The information is essential to identify which person or thing we're talking about
• You can use "that" instead of "who" or "which"
• The relative pronoun can sometimes be omitted
✓ The woman who lives next door is a doctor.
(Which woman? The one who lives next door - this information is essential)
✓ I need a car that is reliable.
(What kind of car? One that is reliable - this defines the type of car needed)
✓ The book (that) you recommended was excellent.
(The relative pronoun "that" can be omitted)
Non-defining Relative Clauses
Non-defining relative clauses (also called non-restrictive clauses) provide extra, non-essential information. The sentence would still be clear and complete without this clause.
• Commas are always used (or dashes/parentheses)
• The information is additional, not essential
• You cannot use "that" - use "who" or "which" instead
• The relative pronoun cannot be omitted
✓ My sister, who lives in Paris, is visiting next week.
(I only have one sister, so the clause just adds extra information)
✓ The Eiffel Tower, which was built in 1889, is Paris's most famous landmark.
(We already know which landmark we're talking about; the clause adds bonus information)
✓ My car, which I bought last year, has been very reliable.
(The speaker has one car; the clause provides additional context)
Quick Comparison
Defining: Students who study hard will pass the exam.
(Only the students who study hard will pass - defines which students)
Non-defining: The students, who study hard, will pass the exam.
(All the students will pass, and by the way, they study hard - adds extra info)
If you can remove the clause and the sentence still makes sense and identifies the noun clearly, it's probably non-defining and needs commas. If removing it makes the sentence unclear or changes the meaning significantly, it's defining and doesn't need commas.
Test Your Understanding
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