Kinematics Explained
Kinematics
Kinematics is the science of motion which treats motion without
regard to the forces which causes it (Craig, 1986).
Kinematics is a heavily research area in robotics where it is
used to manipulate robot arm. So, in a work environment
kinematics is used to manipulated the robot arm to pick up
objects, etc.
Forward Kinematics
In forward kinematics, angles for each joint in the articulated structure
is specified. The following figure further illustrates:

2 Degree of Freedom (DOF) Articulated Structure
If we take the above articulate structure, in forward kinematics the
angles for Angle_1 and Angle_2 are specified which
effectively moves (position and orient (3D env.)) the End-Effector(Gripper,hand).
Inverse Kinematics (IK)
In IK, the position and orientation (3D env.) or the end-effector is specified
instead. The problem in IK is to solve for the joint angles needed to
reach the given end-effector position. This can be done
Algebraically, Geometrically or Iteratively. Refer to my thesis on
solving IK algebraically (specific) and iteratively (generalized).