What

What is a wh-word. We use what to ask questions and as a pronoun and determiner.

What as a question word

We can use what to ask for information about things and actions:

What do you want?

What’s she doing? Tell her to stop at once!

What time are you leaving?

We can also use what in indirect questions:

She asked me what my address was.

I wonder what Jim Barfield is doing these days.

What meaning ‘please repeat’

We can use what in informal situations to ask someone to repeat something if we don’t hear it or understand it:

A:
Did you get the paper?

B:
Sorry, what? (sorry alone would be more polite)

A:
Did you get the paper?

B:
Oh, yes. It’s in the kitchen.

Emphatic questions with whatever and what on earth

We can ask emphatic questions using whatever or what on earth to express shock or surprise. We stress ever and earth:

Joan, whatever are you doing? You’ll give yourself an electric shock! (stronger than What are you doing?)

What on earth is she wearing? She looks awful in that red and white dress! (stronger than What is she wearing?)

What as a pronoun

We can use what as a pronoun to mean ‘the thing(s) that’:

What we need to do is make a list of useful phone numbers. (the thing we need to do)

I can’t decide what to buy Liz for her birthday.

I haven’t got many Beatles CDs, but you can borrow what I have.

We don’t use what as a relative pronoun. We use which:

This is the book which the lecturer mentioned.

Not: … the book what the lecturer mentioned.

What as a determiner

We can use what in exclamations to express a strong feeling or opinion. In this case, we use what as a determiner before a noun or before a/an (+ adjective) + noun:

What lovely flowers!

What a horrible smell!

What a mess!

What … for?

We can use what … for? in two ways. We can use it in informal situations to mean why?:

What did you phone her for? (informal: Why did you phone her?)

We can also use what … for? to ask about the purpose of something:

A:
What’s that buttonfor? (What is the purpose of that button?)

B:
It’s the on–off switch for the radio.

What: typical errors

We don’t use what as a relative pronoun:

The hotel which was least expensive turned out to be the best.

Not: The hotel what was least expensive …

She never asked our permission to use the room, which was very rude of her.

Not: … what was very rude of her.

We don’t use what after words which take a that-clause:

I am very happy that you can come and visit us.

Not: … happy what you can come …