What are the types of?

Your question seems incomplete. Types of what? It could refer to types of government, types of diseases, types of data structures, types of pollution, etc. Could you clarify?

Since it's incomplete, I’ll give a general example: If you were asking about types of pollution, there are air, water, soil, and noise pollution. If you meant types of governments, then monarchy, democracy, dictatorship, etc. The exact answer depends on the missing word.

I think you missed a word in your question. For example, if you meant “types of computers” or “types of banks”, then the answer would vary accordingly. Please recheck the question and update.