Explain that the moment of inertia is rotational analogue of the mass.

As the mass of a body resists a change in its state of linear motion, it is a measure of its inertia in linear motion. Similarly, as the moment of inertia about a given axis of rotation resists a change in its rotational motion.

It can be regarded as a measure of rotational inertia of the body.

It is a measure of the way in which different parts of the body are distributed at different distances from the axis. 

Unlike the mass of a body, the moment of inertia is not a fixed quantity but depends on the orientation and position of the axis of rotation with respect to the body as a whole.