Inverse kinematics (IK) is a method for animating an object or set of objects in relation to each other using an articulated structure of bones. Bones allow symbol instances and shape objects to move in complex and naturalistic ways with a minimum of design effort. For example, inverse kinematics enables you to create character animation—such as arms, legs, and facial expressions—much more easily.

To access the Bone tool, select it in the Tools panel. It is grouped with the Bind tool.

You can add bones to separate symbol instances or to the interior of a single shape. When one bone moves, the other connected bones move in relation to the bone that initiated the movement. When animating using inverse kinematics, you need to specify only the start and end positions of objects; Flash interpolates the position of instances between the start and end points.