the motion of each individual vertex on a mesh for each keyframe can be tedious
as there are many degrees of freedom.
an articulated character model is often described by a set of body parts and
joint angles in a kinematic chain.
body parts are often called bones
joint angles allow control through a reduced set of variables (usually 20 – 25
bones for a human character)
type of modeling is called skeletal animation (or bone animation), and is
supported by the MD3/MD5 format.Source:
Automatic Rigging and Animation of 3D Characters (paper