Relative clauses give us more information about something or someone in a sentence. They are not grammatically essential in a sentence. They may add meaning, but if they are removed, the sentence will still function grammatically.
Relative clauses start with relative pronouns and adverbs, which are used to define or refer back to the noun that precedes them.
The relative pronouns are ‘who’, ‘that’, ‘which’, ‘whose’, and ‘whom’. The relative adverbs are ‘when’ and ‘where’. We use ‘whom’ when it does not refer to the subject of the sentence but the object.
There are two types of relative clause:
Defining relative clauses
Defining relative clauses tell us the specific thing or person we are talking about in a sentence. Defining clauses are not separated by commas or brackets. Defining clauses provide important information about the noun we are talking about. The sentence’s meaning changes greatly if we remove a defining relative clause.
- The girl who invited me is not here yet.
- The shoes that I bought were really expensive.
- This is the woman whose dog saved me.
Non-defining relative clauses
A non-defining clause provides more information about the noun we are talking about in the sentence. Unlike defining relative clauses, non-defining clauses are separated by commas or brackets. Non-defining clauses can be removed from a sentence without affecting the meaning because they simply give us extra details.
- My grandmother, who is 90 years old, lives alone in the countryside.
- My new car, which I bought myself, is compact and good on gas.
- Jucinda, whom I just met, is coming to our house for dinner.
Referring to people
We use ‘who’, ‘whom’, ‘that’, and ‘whose’ to refer to people. We can not use that in non-defining clauses.
- Do you remember that girl that I went to university with?
- Do you know that girl who just started this class?
- Do you remember Kylie, whose mother used to babysit me?
- The little boy, whom I thought was homeless, is back again.
Referring to things
We use ‘which’, ‘that’, and ‘whose’ to refer to things:
- Can I have the book that I lent to you?
- The heavy wind, which is not normal for this time of year, caused damage to our house.
- I told you about this company, whose CEO personally wrote me a letter, the other day.
Referring to time and place
We use ‘when’ and ‘where’ to refer to time and place nouns:
- It was just one of those days when everything goes wrong.
- I am so excited to visit Germany, where Einstein was born, and Austria on our trip in the spring.
This video from explains what relative clauses and pronouns are: