Is a flip book an optical illusion?

Answer 1

Strictly speaking, no, but they do provide the illusion of animation which is not real, as flip books are just books with a series of images that vary slightly from one to the next, so that when the pages are turned rapidly, the pictures appear to animate by simulating motion or some other change.

When we speak of optical illusions we generally mean that you perceive images that differ from objective reality (like 2 lines being one longer than the other when they are the same length really or when 2 people look at a picture and see completely different things, as in the famous instance where depending on how you look at the illustration you see a young lady or an elderly one.)