As an interrogative pronoun:
* Asking for information: "What is your name?"
* Asking for a description: "What did you see?"
* Asking for a reason: "What happened?"
* Asking for a choice: "What would you like to eat?"
As a relative pronoun:
* Introducing a subordinate clause: "I know what you did last summer."
As an exclamation:
* Expressing surprise or confusion: "What! You're leaving already?"
As a noun:
* Referencing something unknown or unspecified: "The what of it all is confusing."
In summary:
"What" is a versatile word that can be used to ask for information, describe something, express surprise, or refer to something unknown. Its meaning depends on the context in which it is used.