Once you have set up a hierarchy using the Link command or a system such as Bones, you can manage it using the Hierarchy panel. This command panel has three tabs:
You use the Pivot tab to adjust the pivot points of objects in the hierarchy. You use the IK tab to manage the behavior of inverse kinematics (IK). You use the Link Info tab to apply constraints to movement within the hierarchy.
See also
Introduction to Hierarchies and Forward Kinematics