Clay animation is an early form of video animation that is still popular today. It consists of using clay pieces as characters and background objects in video animation and moving or "deforming" them between frames to create continuous video motion.
Clay animation is also known as claymation.
Techopedia explains Clay Animation
Before the rise of advanced computer animation technologies, claymation and related physical animation models were the standard for physical animation or 3D animation. Cartoon drawings were often used for 2D animation. This physical animation industry thrived throughout the 1970s and 1980s and into the 1990s as the dominant model until the emergence of computer-generated imagery (CGI) and virtual animation.
Clay animation has many benefits. It preserves a unique authentic look for physical animation. It can also be done with limited resources. However, one of its disadvantages is the labor-intensive process of repositioning clay objects between frames. Industry experts estimate that a 30-minute clay animation video contains thousands of frames, each of which requires small tweaks to the physical clay models.
Even though CGI and virtual or digital animation have largely taken over from physical animation, clay animation still exists and is used for some kinds of projects. For example, smaller studios without access to virtual animation tools may use clay animation. Some projects may use it as a retro or artistic choice. In some cases, designers combine clay animation with high-tech computer animation tools.