Unity’s Animation System has special features for working with humanoid characters. Because humanoid characters are so common in games, Unity provides a specialized workflow, and an extended tool set for humanoid animationsAn animation using humanoid skeletons. Humanoid models generally have the same basic structure, representing the major articulate parts of the body, head and limbs. This makes it easy to map animations from one humanoid skeleton to another, allowing retargeting and inverse kinematics. More info See in Glossary.
The Avatar system is how Unity identifies that a particular animated model is humanoid in layout, and which parts of the model correspond to the legs, arms, head and body.
Because of the similarity in bone structure between different humanoid characters, it is possible to map animations from one humanoid character to another, allowing retargetingApplying animations created for one model to another. More info See in Glossary and inverse kinematics__ (IK)__.