1. What - Used to ask about things
ex - What do you think about the movie?

2. When - Used to ask about time
ex - When will the meeting start?

3. Where - Used to ask about places
ex - Where do you live?

4. Who - Used to ask about people
ex - Who told you that story?

5. Whom - Used to ask about people (object of verb)
ex - Whom did you see in the morning?