Make a selection. > Hierarchy panel > Pivot button
All objects have a pivot point. You can think of the pivot point as representing an object's local center and local coordinate system. The pivot point of an object is used for the following:
Functions as the center for rotation and scaling when you select the Pivot Point transform center.
Sets the default location of a modifier center.
Defines the transform relationship for the object's linked children.
Defines the joint location for inverse kinematics (IK).
You can adjust the position and orientation of an object's pivot point at any time using the buttons in the Adjust Pivot rollout in the Hierarchy panel. Adjusting an object's pivot has no effect on any children linked to that object.
Note: You cannot animate the functions under the Adjust Pivot rollout. Adjusting an object's pivot on any frame changes it for the entire animation. Use caution when adjusting the pivot of an animated object. Adjusting the pivot on one frame might produce unexpected results in another part of the animation.
The Pivot panel has two rollouts: