Frame-by-frame animation is a common form of animation. Its principle is to decompose animation actions into "continuous key frames", that is, draw different contents frame by frame on the time axis and make them play continuously into animation. Because the content of frame sequence of frame-by-frame animation is different, it not only increases the burden of production, but also has a large amount of files, but also has obvious advantages: frame-by-frame animation is very flexible and can express almost anything it wants, and it is similar to the playback mode of movies, which is very suitable for delicate animation. For example, people or animals make sharp turns, hair and clothes flutter, walk, talk, and exquisite 3D effects.
Frame-by-frame animation was invented by an unknown technician as early as 1907. At that time, this wonderful method made a splash in early movies. At that time, this technology was still unknown. Later, Emile Cohl of the French company Gomon discovered this secret and made many cartoons. Among them, Little Faust is a frame-by-frame puppet animation, which is a masterpiece of early frame-by-frame animation. Later, with the improvement of frame-by-frame animation, a large number of cartoons appeared.
Source: Baidu Encyclopedia: Frame by Frame Animation