A system combines objects, linkages, and controllers to produce an object set that has behavior as well as geometry. Systems help you create animations that would be much more difficult or time-consuming to produce using features independently. Systems can range from simple object generators to full-scale subsystem programs.

Bones creates a hierarchically linked set of bones and joints.
You can transform and animate bones using both forward and inverse kinematics. See Animating with Forward Kinematics and Inverse Kinematics (IK).
Ring Array creates a ring of boxes.
Sunlight creates and animates a directional light that follows the geographically correct angle and movement of the sun over the earth at a given location.
Daylight creates an assembly with a sky and a sun. Using the Get location function you can create and animate a light that follows the geographically correct angle and movement of the sun over the earth at a given location.
Biped creates a two-legged character skeleton designed for animation.
Systems are primarily intended for plug-in component software. Additional systems might be available if your configuration includes plug-in systems.
You can externally reference system objects in your scene. For more information, see XRef Objects.