The relative pronouns in English are who, which, that and whose. Whom is also used by some people but is considered by many to be too formal.
A relative pronoun introduces a relative clause:
This is the table which I bought.
‘This is the table’ = the main clause; ‘I bought’ = the relative clause; ‘which’ = the relative pronoun joining the two clauses
We use who or that when we talk about people.
Who is more formal than that.
This is the man who helped us.
This is the man that helped us.
We cannot use what:
We use which or that when we talk about things
Which is more formal than that.
It's the watch which my husband bought me for my birthday.
It's the watch that my husband bought me for my birthday. (less formal)
|In informal speech, we can omit which and that when the pronoun refers to the object of the sentence.||
It's the watch my husband bought me for my birthday.
In this sentence, 'the watch' is the object of the verb 'bought' so we don't need to use that or which.
|We cannot omit which and that when the pronoun refers to the subject of the sentence.||
It was the man that sold me the car.
In this sentence, 'the man' is the subject of the verb 'sold' so we need to use that or who.
|We use whose to show possession.||John, whose brother was also a musician, plays over 100 concerts every year.|
See also: Relative clauses
|Practise this grammar (pre-inter / intermediate): Exercise: relative pronouns – who, which, that, where, whose|