How does animation create the illusion of movement?

In an animated film, drawn or digital characters walk, dance, and express emotion as if they were truly alive. It feels like magic, giving life to something that is really just artwork. But animation is not magic. It is a craft built on a simple and powerful idea, one closely related to how all film works. An animator does not make a drawing move. Instead, the animator creates the clever illusion that it moves.

The foundation of animation is the still image. An animated sequence is made of many separate pictures, and each one is slightly different from the one before it. Picture a character raising an arm: the animator creates one image with the arm low, then another with the arm a little higher, then another higher still, and so on. Each individual image is completely motionless. The movement does not exist in any single picture. It exists only in the differences between them.

The secret ingredient is speed. When these slightly different still images are shown one after another, fast enough, our eyes and brain blend them together. We stop seeing a series of separate drawings and instead perceive one smooth, continuous motion. This is the same optical effect that makes live-action film work. The brain holds onto each image for a brief moment and merges it with the next, filling in the movement between them.

The simplest example of this principle is a flipbook: draw a slightly changing figure on each page, flip the pages quickly, and the figure appears to move. Traditional animation extended this idea, with artists creating large numbers of drawings to be filmed in sequence. Modern animation often uses computers to build and pose characters, but the core idea has never changed. Whether hand-drawn or digital, animation is always a rapid sequence of still images, and the motion lives in our perception.

This article was written using information from Wikipedia.