What Is The Difference Between 'What' And 'Which'?

Non-native speakers of English often are confused between the use of 'what' and 'which' in a sentence. Look at these two sentences:

1. What is your name?
2. Which is your name?

Though both the sentences are grammatically correct, we always use the first sentence that starts with 'what'. The reason is 'what' refers to an open set and 'which' refers to a closed set. In the first sentence (What...), the speaker has no chance of guessing any name. In the second sentence (Which...), the speaker may have a few names in mind or on the list. 'Which' generally suggests there are two or more possibilities, and the person asking 'which' probably knows what they are. Look at these examples:

'What' refers to an open set:
- What is the name of the examiner?

'Which' refers to a closed set:

- Which (of the) countries have you visited?

In the above sentences, it is not possible to replace 'which' with 'what'. If the choice is clearly restricted, then 'which' is the better choice.

Both 'what' and 'which' are interrogative as well as relative pronouns.
As an interrogative pronoun, 'what' in a question suggests unlimited possibilities. Here are a few examples:

- What are you going to do this weekend?

- What is your favourite picnic spot?

'Which' in a question suggests a definite, limited list of alternatives. Look at these examples:

- Which game do you like the most?
Both the speaker and the listener have a few games in mind.

As a relative pronoun, 'what' means unlimited possibilities:

- The examiner asked the student what his name was.

'Which' as a relative pronoun is specific:

- I went to Goa, which is a beautiful place.

'What' is used in a range of expressions, all giving the idea of 'no limits'.

"what" is choosing from the unknown , "which" is choosing from the known .

When you have more choices to choose, then use 'What'. If you have limited or specified choices, then use 'Which'.

Basically what is used when you have unlimited options and which is used when you have limited option. For Example if you go to buy a pizza, a person who is selling pizza would ask that which kind of pizza do you want because there are four to five types of pizza's. But on the other hand lets take an example what is your name because a lot of names are there

Both "what" and "which" are relative and interrogative pronouns. Sometimes they are very close in meaning, eg you could say "What colour/ which colour do you like best?"

Usually, though, "what" in a question suggests unlimited possibilities, eg "What do you like doing?" - the answer could be almost anything. "Which do you like?" on the other hand, shows a definite, limited list of alternatives (basketball or tennis, say.)

As relative pronouns, they are quite different. "What" again means unlimited possibilities: "She asked what my name was," " I don't know what to do." "Which" is specific: "I live in the countryside, which is very pleasant," or "I don't know which jacket to buy."

"What" is used in a range of expressions, all giving this idea of "no limits:" "What about...?" "What if..?" or used as a substitute for any other word: "I saw whatshisname this morning" or "I bought a whatyoucallit."

I understand it)
think that next lesson would be good for me)