Long before technology offered the possibility to create sophisticated animations, the illusion of movement fascinated the public and many techniques were invented to create that illusion.
The first attempts at creating animations without modern technology were numerous, from stroboscopic discs to magic lanterns. However, the animations had to be very short as they consisted in a succession of different frames that gave the illusion of movement.
Cinematography changed this with cell animations where frames where drawn separately (independently from the backgrounds to gain time) and combined to create films (e.g. Snow White and the Seven Dwarfs produced by Walt Disney in the 30s).
Computer animations followed with techniques that are improving constantly, both in 2D and 3D.
However, illusion is still at the heart of animations:
First of all because the first attempts at creating the illusion of movement have inspired modern methods with the idea of using frames in succession.
But even when new computer technologies use different methods, the idea of illusion remains although it might be in a different form and might not rely so much on optical illusion. For instance Adobe Character Animator enables the creator to use human movements to animate the characters. However, when we see the animated illustration, even if we do not know how this was created, we still know that there is some illusion behind the scene.
In fact, illusion is what makes animations so interesting. Whether it is today with sophisticated software or a long time ago with a magic lantern, we like the idea of being tricked and marvel at how realistic something unreal can look.
Source:
https://en.wikipedia.org/wiki/Animation
https://www.masterclass.com/articles/a-guide-to-the-history-of-animation
Catherine Roux Degree in Illustration 