Definition / Explanation
Non-defining relative clauses add extra information about a person or thing that is already identified. They do not tell us which one; they simply give additional detail. Because the information is extra, we separate it with commas in writing. In speech, the clause is also marked by pauses. This is different from defining relative clauses, which are necessary to identify the noun and therefore do not use commas. Non-defining clauses are common in descriptive and informational writing.
Key Rules
- Use who, which, whose, and sometimes where in non-defining relative clauses.
- Put commas around the clause if it comes in the middle of the sentence.
- Do not use that in standard non-defining relative clauses.
- The clause adds extra information, not essential identification.
- The sentence usually still makes basic sense if you remove the clause.
Examples
- My brother, who lives abroad, is visiting.
- The car, which I bought used, is reliable.
- Our office, which is near the river, closes at six.
- Anna, whose father is a doctor, studies law.
- The hotel, where we stayed last year, has reopened.
Common Mistakes
- ❌ My brother, that lives abroad, is visiting. -> ✅ My brother, who lives abroad, is visiting.
- ❌ The car which I bought used is reliable. -> ✅ The car, which I bought used, is reliable.
- ❌ Anna, who father is a doctor, studies law. -> ✅ Anna, whose father is a doctor, studies law.