What's the difference between illusion, delusion, and hallucination?

Without looking the words up, here is my take on them. Illusions are things that appear to be different from what they are. Optical illusions are an example. A delusion is something we believe that has no basis in reality. A hallucination is something that we imagine perceiving with our senses that is not really there.

I agree with @LostInParadise

@LostInParadise is spot on.

An illusion is outside of you. A delusion inside of you. A hallucination is both or either.