What are IK and FK Modes

What is IK

IK (Inverse Kinematics) refers to a process utilized in 3D computer graphic animation. In this process, the parameters of each articulation, in a jointed flexible object (a kinematic chain), will be automatically calculated to achieve a desired pose, especially when the end point moves.

IK is how the child node movement affects all the parent nodes' position and orientation values.

Child node selected.	Offsets of all nodes in the chain gets affected.

What is FK

FK (Forward Kinematics) is how the positions and orientations of particular parts of a model are calculated, together with any information of the articulated model.

FK refers to the effect on the child nodes as the parent moves or rotates.

Parent node selected.	Only parent's offset gets affected.