Inverse kinematics (IK) is a positioning and animation method that is built on top of the concepts of hierarchical linking. To understand how IK works you must first understand the principles of hierarchical linking and forward kinematics.

Inverse kinematics starts with linking and pivot placement as its foundation and then adds the following principles:

• Joints are constrained with specific positional and rotational properties.
• Position and orientation of parent objects is determined by the position and orientation of child objects.

Because of these added constraints, IK requires greater thought about how you link your objects and place pivots. Where many different solutions for linking objects might be suitable for forward kinematics, there are usually just a few good solutions for any given IK approach. The best solution depends on consideration of both the nature of the hierarchy, and how that hierarchy will be animated.

Inverse kinematics is often easier to use than forward kinematics and you can quickly create complex motions. However, you sacrifice some of your control to the automation of the IK functions.