What are 'secondary actions' in animation?

Secondary actions in animation refer to minor actions that complement and enhance the primary motion, providing greater depth and realism to the characters or elements involved. These subtle movements can include various gestures, expressions, or reactions that occur alongside the main action, adding nuance and interest to the scene. For instance, if a character is walking, a secondary action might be the slight sway of their arms, a shift in their weight, or the flick of their hair, all of which help to create a more believable and engaging animation. By incorporating these secondary actions, animators can convey personality and emotion, making the primary action feel more natural and impactful.