1. Relative clauses John is the man who has won the lottery.
They are clauses that qualify a noun.
They are introduced by a word which is called RELATIVE PRONOUN.
This pronoun both
- substitutes the noun the clause qualifies
- it is the subject or a complement in the sentence it introduces
Relative clauses
John is the man who has won the lottery.
subject
I can’t find the place where I left my glasses.
complement

2. Relative clauses The most common relatives are: who
It substitutes a person.
which
It substitutes an animal or a thing.
Relative clauses
that
It substitutes a person, an animal or a thing.
whose
It substitutes a possession.
when
It substitutes a time.
where
It substitutes a place.

3. There are two different types of relative clauses:
Defining relative clauses.
They provide important information which is needed to understand the sentence.
Relative clauses
Are you travelling to Mexico? That’s the place where I spent my honeymoon.
The man that I was talking to was my English teacher.
Do you remember the lady whose dog bit you?

4. b)
Non-defining relative clauses.
They provide additional information to the main sentences.
They must be written between commas.
Relative clauses
There is a beautiful park in Barcelona, where I met my husband, which is called Parc Güell.
Ms. Jones, to whom I was talking yesterday, is coming on Monday.

5. Relative clauses REMARK!!!
OMISSION OF THE RELATIVE PRONOUN.
The relative pronoun is omitted if: a)
It is not the subject of the sentences it introduces.
The factory that closed last month is over there.
Tell me the name of the girl you were talking to.
that
Relative clauses b)
It is not preceded by a preposition.
What’s the name of the hotel in which you stayed last week?
Is that the man you lived with in Paris?
that c)
It is not a non-defining clause.
REMARK!!!
WHOSE is never omitted