By default, a function curve progresses at a constant speed from start to end. A TimeWarp curve acts as a speed measurement. Applying a TimeWarp curve over a function curve and changing its shape changes the timing of an animation.

You can add additional keyframes and change the shape of the TimeWarp curve to slow down, speed up, or reverse the animation.

TimeWarp curves are applied as a separate curve over a function curve, so altering a TimeWarp curve does not change the function curve. The modifications you make with a TimeWarp curve only become permanent if you merge them with a function curve.