Short answers, pulled from the story.
The phenakistiscope was introduced in 1833 as a stroboscopic disc that required viewers to look into a mirror while spinning a disk with sequential images painted on it. The rapid succession of pictures created an illusion of movement that captivated audiences for decades.
Émile Cohl created Fantasmagorie in 1908 which stands as the oldest known example of complete traditional hand-drawn animation on standard cinematographic film. This film followed J. Stuart Blackton's release of The Haunted Hotel in 1907 which popularized stop motion techniques during the silent era.
Walt Disney Studios premiered Snow White and the Seven Dwarfs in 1937 which remains one of the highest-grossing traditional animation features ever made. The enormous success of Mickey Mouse placed Disney at the forefront of the animation industry and started the golden age of American animation lasting until the 1960s.
The so-called 3D style became dominant following the success of Toy Story in 1995 which was the first computer-animated feature in this specific style. Most cel animation studios switched to producing mostly computer-animated films around the 1990s because it proved cheaper and more profitable than traditional methods.
In 2010 the animation market was estimated to be worth circa US$80 billion while by 2021 the value had increased to an estimated US$370 billion. Animated feature-length films returned the highest gross margins around 52% of all film genres between 2004 and 2013.