Animation Using Bézier Curves
"A Bézier curve is a parametric curve frequently used in computer graphics and related fields. Bézier curves are also used in animation as a tool to control motion. In animation applications, such as Adobe Flash and Synfig, Bézier curves are used to outline, for example, movement. Users outline the wanted path in Bézier curves, and the application creates the needed frames for the object to move along the path. "
(from Wikipedia)
Drag the points to change the path of the Green Worm.