What does the slow in and slow out principle acknowledge in animation?

The principle of slow in and slow out acknowledges the importance of timing in animation. This principle highlights that objects in motion do not simply start and stop abruptly. Instead, they typically accelerate at the beginning of their movement and decelerate before coming to a halt, creating a more natural and fluid motion.

By implementing slow in and slow out, animators add realism to their movements, as it closely mimics how objects move in the real world, responding to forces such as gravity and momentum. This does not just apply to the physical properties of motion but also enhances the timing and pacing of the animation, making it more engaging for the viewer. Animation that employs this principle often feels more lifelike because it reflects the nuanced timing inherent in natural movement, capturing attention and communicating intent more effectively.