In history-independent inverse kinematics (HI IK) and the IK Limb Solver, the IK goal is the object associated with the end joint of a kinematic chain. By default, its name is IK Chain01.
The kinematic chain is a single branch of a hierarchy used for animation with inverse kinematics (IK). The chain starts with the end joint and travels up through ancestors until it reaches the start joint. When you move the IK goal, the IK solver then uses IK calculations to move and rotate all other objects in the kinematic chain to react to the object you moved.