We use question tags when we are looking for confirmation.
(eg. He is famous, isn’t he? —> we want the person that we are talking to, to confirm what we are saying)

If we say something positive, the question tag must we negative. (He is famous, isn’t he?)
If we say something negative, the question tag must be positive. (He isn’t famous, is he?)

We can use different auxiliary verbs such as : do / have / be

Examples :

– He won’t come, will he?
– She has a cat, doesn’t she?
– They are happy, aren’t they ?