What is animation? This study is done as a process for answering the question. Until now, animation has been studied as a means of industry, media characteristics, aesthetics, and education, but no research has been done on what animation is. It is because we are mistaken that we already know the definition of animation and we know what animation is through the well-known definition of animation. However, these unverified definitions of animation have obscured the true identity of the animation and hindered the development of the animation. This study theme seems slightly provocative but I suggest the answer about what animation is. Animation is making artificial movement on virtual space using still images. This suggested definition of animation should be revised and refuted in the future. But through this process, we can realize the essence of the art medium of animation and set a milestone for what orientation we should have.