Relative vs Non-Defining Clauses: Key Grammar Rules & Examples
A relative clause gives extra information about a noun; if it’s essential to the meaning it’s defining, if it’s optional and framed by commas it’s non-defining.
People mix them up because commas feel optional in fast typing, and removing “that” or “who” seems stylish, but it can change the whole point of a sentence—especially in LinkedIn bios or pitch decks where precision sells.
Key Differences
Defining clauses narrow the noun: “The laptop that crashed is on sale.” Non-defining clauses add bonus info: “My MacBook, which I love, just updated.” No commas = defining; commas = non-defining.
Which One Should You Choose?
Choose defining when the detail is vital for identification. Pick non-defining when the noun is already specific and you’re adding flavour. In emails to investors, defining keeps focus; in customer stories, non-defining adds warmth.
Examples and Daily Life
Defining: “Clients who pay annually get priority.” Non-defining: “Stripe, which powers our checkout, just released a new API.” Notice the comma flip changes urgency to aside.
Can I use “that” in non-defining clauses?
No. Reserve “that” for defining clauses; non-defining clauses need “which” or “who” and commas.
Are commas enough to signal the difference?
Exactly—those two tiny marks switch a clause from essential filter to optional aside.
Does it matter in SEO headlines?
Yes. A defining clause can tighten keyword focus; a non-defining one can dilute it with extra detail.