We use "which" as a determiner to ask a question about a specific group of people or things:

Which restaurant did you go to?
Which countries in South America have you visited?

When we are asking a general question we use "what" as a determiner:

What films do you like?
What university did you go to?

Section: 

Comments

What's the difference between saying "WHICH restaurant did you go to" and "WHAT university did you go to" if there are a lot of universities and and lot of restaurants? Can't I use the same word, "what" or "which" for both? Thank you.

Hello Imjustaguy,

We use 'which' when we have a specific set or group in mind and 'what' when we don't have a specific set or group in mind. This means that you could use 'what restaurant' or 'what university' in a context when you did not have a specific group in mind, and 'which restaurant' and 'which university' when you do.

For example, in Boston in the USA, there are several famous universities (Harvard, MIT and others). If you're speaking with someone about their university studies in Boston but she hasn't mentioned where she studied, 'which' would be the form you should use to ask the question ('Which university did you go to?'). You could say 'what', but it would sound strange because there is a specific set of universities that has been mentioned.

On the other hand, imagine you've just met someone who is the first person to go to university in her family, but you have no idea where and there is no other specific set of universities that has been mentioned. In this case, 'what' would be the form you should use.

I hope that helps clarify the matter for you.

All the best,
Kirk
The LearnEnglish Team

Thank you Kirk, I was about to ask the same.

Hello Peter,

Could you please check if my understanding is correct:
What films do you like?
Which film did you watch?

Thank you very much
Basem

Hello Basem,

Those sentences are correct. However, you could also say 'Which films do you like?' if you were standing in front, for example, of a collection of films, and you could say 'What films did you watch?' if you were asking in general without any set of films in mind. The key is whether you are asking 'out of these possible films' (which) or 'out of all films without limit' (what).

 

Best wishes,

Peter

The LearnEnglish Team

Very clear! Thank you so much
Basem

Why used what instead of which (university did you go to?)

Hello MAMAD,

The answer to this is on the page above:

We use "which" as a determiner to ask a question about a specific group of people or things

When we are asking a general question we use "what" as a determiner

 

Best wishes,

Peter

The LearnEnglish Team

Hi,

I understand that what is general and which is a limited group or more specific.

My question is why as a native speaker is "What's your blood type" more natural sounding that "Which is your blood type?"

I know that I can say "Which blood type do you have?" I'm just having trouble explaining why "which is your blood type?" sounds wrong.

Thanks

Hi teacherwithqs,

We generally use 'which' when there is a limited set of options and they are presented before us. Thus, if you were simply asking a person about their blood type then you would say 'What...?' However, if you had, say, a chart in front of you with the various blood types on it then you would tend to say 'Which...?'

One way to think of this is that 'Which...?' really means 'Which of these...?'

 

Best wishes,

Peter

The LearnEnglish Team

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