What (pronoun)

1. Asking for information specifying something.
2. Referring to something that is unknown.
3. Used to express surprise, confusion, or disbelief.
4. Used to introduce a clause.

Origin:

Old english hwæt, of germanic origin; related to dutch wat and german was.

Examples:

1. What is your name?
2. I don't know what to do.
3. What! You're leaving already?
4. Tell me what you want to do tomorrow.
5. I can't remember what I was going to say.