View Forward Kinematics
Forward Kinematics (FK) is effectively rotational motion imparted via direct means. Take the arm example: in order to place the hand on a handle of a door would be straightforward with inverse kinematics (IK)—you simply move the hand from the starting postion to the door handle. The rest of the arm joints follow suit. However, before IK, you would have to manually rotate each joint of the arm, in a natural motion, to achieve the same result. In fact, you might see from three to ten times as much animation work to achieve what is one step with IK. That said, many animators tend to prefer FK over IK for arms and other limbs, though most animators seem to universally prefer IK for leg motion. The FK/IK setting allows you to decide when you want to use either one, and you can even animate the blend between the two methods for maximum control.