When you learn English, you quickly discover that not all sentences are simple. Some sentences contain extra information added inside them. This is where relative clauses become very useful. In English, there are two main types: defining relative clauses (also called restrictive) and non-defining relative clauses (also called explanatory). Understanding the difference will help you speak and write much more naturally.
Simple Examples to Get Started
Let us start with two short sentences that look similar but mean very different things:
- The man who called me is my boss.
- My boss, who called me, is very kind.
Do you see the difference? The first sentence tells us which man we are talking about. The second sentence simply adds extra information about a person we already know. This small difference changes the meaning completely.
The Key Elements of Defining and Non-Defining Relative Clauses
Let us now look at the main components of each type.
Defining Relative Clauses
A defining relative clause gives essential information. Without it, the sentence loses its meaning or becomes unclear. We do not use commas with this type.
- The book that I bought yesterday is very interesting. (Which book? The one I bought yesterday.)
- Students who study regularly get better results. (Which students? Those who study regularly.)
- The city where I was born is in the south. (Which city? The one where I was born.)
Notice that in defining clauses, you can use that instead of who or which. This is very common in spoken English.
Non-Defining Relative Clauses
A non-defining relative clause adds extra information that is not essential. If you remove it, the sentence still makes perfect sense. We always use commas with this type. Also, you cannot use that here.
- My sister, who lives in London, is a doctor. (We already know who my sister is.)
- Paris, which is the capital of France, is very beautiful. (Paris is already a specific, unique place.)
- Mr. Smith, whom I met last year, is now my colleague.
The Role of Relative Pronouns
The relative pronoun you choose depends on what the clause refers to. Here is a simple table:
| Pronoun | Used for | Defining | Non-Defining |
|---|---|---|---|
| who | people | yes | yes |
| which | things / animals | yes | yes |
| that | people / things | yes | no |
| whose | possession | yes | yes |
| where | places | yes | yes |
| whom | people (formal) | yes | yes |
Why This Grammar Point Matters
You might wonder: why should I learn this? The answer is simple. These two types of clauses appear everywhere in English. They are in newspapers, books, emails, and daily conversations. If you confuse them, you might give the wrong message to your reader or listener.
For example, look at these two sentences:
- My children, who love football, play every weekend. (I have children. They all love football.)
- My children who love football play every weekend. (I have several children. Only those who love football play every weekend.)
The commas completely change the meaning. This is why punctuation is so important here.
Comparison with Other Languages
If you speak French or Spanish, you might find some similarities, but also some important differences.
| Feature | English | French | Spanish |
|---|---|---|---|
| Defining clause marker | that / who / which | qui / que | que / quien |
| Non-defining clause | commas required, no ‘that’ | commas used, same pronouns | commas used, same pronouns |
| Use of ‘that’ | only in defining clauses | no equivalent of ‘that’ | no equivalent of ‘that’ |
| Omitting the pronoun | possible in defining clauses | not possible | not possible |
One big difference: in English, you can sometimes omit the relative pronoun in a defining clause when it is the object. For example: ‘The film I watched was great’ instead of ‘The film that I watched was great.’ This is not possible in French or Spanish.
A Complete Example
Let us look at a short paragraph that uses both types of clauses:
‘My neighbour, who is a retired teacher, has a dog. The dog, which is very friendly, loves playing in the garden. Every morning, the children who walk past our house stop to pet it. It is the kind of dog that everyone loves immediately.’
- My neighbour, who is a retired teacher — non-defining (extra info about my neighbour)
- The dog, which is very friendly — non-defining (extra info about the dog)
- the children who walk past our house — defining (tells us which children)
- the kind of dog that everyone loves — defining (tells us which kind of dog)
Key Points to Remember
- Defining clauses give essential information — no commas, and you can use that.
- Non-defining clauses give extra information — always use commas, never use that.
- The relative pronoun depends on the noun it refers to: person, thing, or place.
- In defining clauses, the pronoun can sometimes be omitted when it is the object.
- Commas are not just punctuation — they change the meaning of your sentence.
Sources
- Swan, M. (2005). Practical English Usage (3rd ed.). Oxford University Press.
- Quirk, R., Greenbaum, S., Leech, G., and Svartvik, J. (1985). A Comprehensive Grammar of the English Language. Longman.
- Hewings, M. (2013). Advanced Grammar in Use (3rd ed.). Cambridge University Press.