Most simple animation in Flash is done using a process known as
tweening. Tweening is short for "in between" because it
refers to filling in the frames between two keyframes so that a
graphic displayed in the first becomes the graphic displayed in
the second.
For example, suppose you wanted to animate the changes the circle
in the previous set of images goes through.
Traditional "frame by frame" animation would require
that each of the in-between frames, starting with the circle on
the left and changing color, shape, location, and transparency,
be hand drawn. Flash tweening can generate the frames automatically.
Tweening can be applied to several properties of an object, including
motion, shape, color, rotation, size and skew. The movie below shows
tweening as applied to the set of keyframes in the previous set
of images.
