We can use relative clauses to join two English sentences, or to give more information about something.
We will stay at a hotel. The hotel is next to the beach.
We will stay at a hotel which is next to the beach.
Defining relative clauses (also called identifying relative clauses or restrictive relative clauses) give detailed information defining a general term or expression. Defining relative clauses are not put in commas.
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Relative Pronouns & Adverbs
We will stay at a hotel. The hotel is next to the beach.
We will stay at a hotel which is next to the beach.
Defining Relative Clauses
This is a book that I bought yesterday.
(If I don't say 'that I bought yesterday', then we don't know which book I mean).Non-Defining Relative Clauses
Non-defining relative clauses (also called non-identifying relative clauses or non-restrictive relative clauses) give additional information on something, but do not define it.
Non-defining relative clauses are put in commas.
Saint Petersburg, which has some fantastic museums, is called the cultural capital of Russia. ('which has some fantastics museums' gives us extra information).
why
Who refers to people, and sometimes to pet animals.
Do you know the man who talked to me?
We use who to introduce defining and non-defining relative clauses:
Which refers to animals and to things. We use it to introduce defining and non-defining relative clauses. We always use which to introduce relative clauses when they refer to a whole sentence or clause.
He received the letter which he was waiting for.
Whose indicates possession by people and animals. In more formal styles we can also use it for things.
The woman whose wallet was broken was sad.
We use whom in formal styles or in writing to refer to people when the person is the object of the verb. It is much more common in writing than in speaking.
He was a brilliant actor whom I had known since his first appearance on the stage.
We use that instead of who, whom or which in relative clauses to refer to people, animals and things. We use it to introduce defining clauses only.
That is more informal than who, whom or which.
Don’t take money that doesn’t belong to you.
when, where, why
In informal language, we often use where, when or why to introduce defining relative clauses instead of at which, on which or for which.
More information: Cambridge Dictionary
Do you know the man who talked to me?
We use who to introduce defining and non-defining relative clauses:
Which refers to animals and to things. We use it to introduce defining and non-defining relative clauses. We always use which to introduce relative clauses when they refer to a whole sentence or clause.
He received the letter which he was waiting for.
Whose indicates possession by people and animals. In more formal styles we can also use it for things.
The woman whose wallet was broken was sad.
We use whom in formal styles or in writing to refer to people when the person is the object of the verb. It is much more common in writing than in speaking.
He was a brilliant actor whom I had known since his first appearance on the stage.
We use that instead of who, whom or which in relative clauses to refer to people, animals and things. We use it to introduce defining clauses only.
That is more informal than who, whom or which.
Don’t take money that doesn’t belong to you.
when, where, why
In informal language, we often use where, when or why to introduce defining relative clauses instead of at which, on which or for which.
| relative adverb | meaning | use | example |
|---|---|---|---|
| when | in/on which | refers to a time expression | the day when we met him |
| where | in/at which | refers to a place | the place where we met him |
| why | for which | refers to a reason | the reason why we met him |
More information: Cambridge Dictionary
