Why add void before methods?

Question

Why do you need to add the keyword void before certain methods. I know it means the method returns nothing (or at least that's what I think it means), but why should you add void even if you already know the method is supposed to return nothing?

Answer 1

To tell the compiler that the method is supposed to return nothing.

This kind of redundancy allows the compiler to tell you if you make a mistake somewhere.
(eg, forgetting a return statement)