Relative Clauses: Defining and Non-defining

What You Will Learn

You'll understand when to use defining relative clauses (essential information) versus non-defining relative clauses (extra information), and why commas matter more than you think.

Explanation (with real-life context)

Imagine you're telling a friend about a job interview. There's a big difference between:

• "The interviewer who wore glasses asked tough questions." (defining — you're identifying which interviewer)
• "My interviewer, who wore glasses, asked tough questions." (non-defining — you already know who, glasses is just extra info)

The defining relative clause is like saying "I need to tell you which one." The non-defining relative clause is like an aside — you could remove it and the sentence still makes sense.

Key difference: Defining clauses have NO commas. Non-defining clauses MUST have commas around them.

Examples (natural sentences from daily life)

Defining (identifying which person/thing):
- The café that opens at 6 AM is where I study. (Which café? The one that opens at 6 AM.)
- The message you sent yesterday got lost. (Which message? The one from yesterday.)
- People who exercise regularly sleep better. (Which people? The ones who exercise.)

Non-defining (adding extra info about someone/something already known):
- Starbucks, which has locations worldwide, just opened here. (We know which company; the clause adds info.)
- My best friend, who studied abroad, finally came home. (You know who I mean; the clause is bonus info.)
- The meeting, which lasted three hours, was exhausting. (We know the meeting; the info is extra.)

Common Mistakes

❌ "The person who called me yesterday, was my boss." (Don't use comma in defining clause)
✅ "The person who called me yesterday was my boss."

❌ "My boss who is kind, always listens." (If you know who your boss is, remove the comma)
✅ "My boss, who is kind, always listens."

❌ "The house that we bought it last year..." (Don't repeat the subject)
✅ "The house that we bought last year..."

Quick Tips

• Test it: Remove the clause. If the sentence still makes sense and is specific, use defining (no commas). If it's just extra info, use non-defining (add commas).
• Relative pronouns: Use who (people), which (things), that (both, mainly in defining), whose (possession).
• In non-defining, avoid that. Always use who or which: My laptop, which is old, still works. (not "that")