Read about relative clauses below. Then, when you are ready, try these relative clauses practice exercises.
Using defining relative clauses
These work a bit like adjectives - they are used to give information about a person, place or thing. The information is necessary - without this information we don't know what you are talking about. Use relative clauses after the thing you are defining - here the man:
I hate the man who's talking to Sarah.
The man who's talking to Sarah is so annoying!
Relative Pronouns (and related words)
For things we say which and for people we say who. For places, we say where and for possessions (e.g. my car, his brother) we say whose + noun.
I like the dress which your sister is wearing.
I like the man who is talking to your sister.
I like the shop where you bought that dress.
I like the woman whose brother I met.
Rules for defining relative clauses
When there's no comma (,) before which or who, we can use that instead (for use of commas, see the next lesson - non-defining relative clauses). That is more informal.
I like the dress that your sister is wearing.
Not using who/which
You don't need to say who or which if there is a noun (the subject of the verb) afterwards.
That's the man (who) I love.
We don't need who here because the verb love has a subject (I).
That's the man who loves me.
We need who here because there is no noun afterwards (who is the subject of the verb love).
After a preposition or as the object of a verb, we should use whom for people. However, this is less and less common nowadays, and in informal English most people use who.
I was talking to the student with whom you went on holiday.
This is correct, but sounds very formal and unnatural.
I was talking to the student who you went on holiday with.
This isn't grammatically correct, but it sounds much more natural. (It's probably even more natural to remove who completely here - see the rule above about not using who.)
Now try these relative clauses practice exercises.