Kinematics (Greek κινειν, to move) is a branch of mechanics which describes the motion of objects without the consideration of the masses or forces that bring about the motion. By contrast, dynamics is concerned with the forces and interactions that produce or affect the motion.
Kinematics studies how the position of an object changes with time. Position is measured with respect to a set of coordinates. Velocity is the rate of change of position. Acceleration is the rate of change of velocity. Velocity and Acceleration are the two principal quantities which describe how position changes.
The simplest application of kinematics is to point particle motion (translational kinematics or linear kinematics). The description of rotation (rotational kinematics or angular kinematics) is more complicated. The state of a generic rigid body may be described by combining both translational and rotational kinematics (rigid-body kinematics). A more complicated case is the kinematics of a system of rigid bodies, possibly linked together by mechanical joints. The kinematic description of fluid flow is even more complicated, and not generally thought of in the context of kinematics.