For instance, what is it called when your doing a drawing and the character is making fast movement, so to signify the movement, you'll draw swoosh lines. Or if the hand is moving back and forth, you'll drawing the main hand and two outlines of the hands, to show it's in motion. Another example would be if someone is spinning around in place extremely fast, and you'll see outlines of the character in a spinning motion? I see this used alot in comics like Garfield.
I hope you have some sort of clue what I'm saying.





