Relative clauses – defining relative clauses

Are you the one who sent me the email?The phone which has the most features is also the most expensive.
This is the video that I wanted to show you.
The person they spoke to was really helpful.

Grammar explanation

Relative clauses give us information about the person or thing mentioned. 

Defining relative clauses give us essential information – information that tells us who or what we are talking about.

The woman who lives next door works in a bank. 
These are the flights that have been cancelled.

We usually use a relative pronoun or adverb to start a defining relative clause: who, which, that, when, where or whose.

who/that

We can use who or that to talk about people. that is more common and a bit more informal.

She's the woman who cuts my hair.
He's the man that I met at the conference.

which/that 

We can use which or that to talk about things. that is more common and a bit more informal.

There was a one-year guarantee which came with the TV.
The laptop that I bought last week has started making a strange noise!

Other pronouns

when can refer to a time.

Summer is the season when I'm happiest.

where can refer to a place.

That's the stadium where Real Madrid play.

whose refers to the person that something belongs to.

He's a musician whose albums have sold millions. 

Omitting the relative pronoun

Sometimes we can leave out the relative pronoun. For example, we can usually leave out who, which or that if it is followed by a subject.

The assistant [that] we met was really kind.
   (we = subject, can omit that)

We can't usually leave it out if it is followed by a verb.

The assistant that helped us was really kind.
   (helped = verb, can't omit that)

Pronouns

"Put your question in the box"