A measurement of how resistant to angular (rotational) acceleration an object is. The moment of intertia depends on the mass, position of axis of rotation, and shape of the object. In general, however, the moment of intertia is dependant on the concentration of mass a distance from the axis of rotation. For example, if you have two discs, equal radius, depth, and mass, but one is hollow (like a ring), the ring will have a greater moment of intertia. Like mass in trasnlational kinematics, objects with a greater moment of intertia require more torque to have the same angular acceleration. However, if two objects are rotating at the same angular velocity, then the object with a greater moment of intertia will have more kenetic energy.