The moment of inertia, often denoted by �I, is a measure of an object's resistance to changes in its rotational motion about a particular axis. It is similar to mass in linear motion, but in rotational motion.

The moment of inertia depends on both the mass of the object and its distribution of mass around the axis of rotation. The farther the mass is from the axis of rotation, the larger the moment of inertia.

For a continuous body, the moment of inertia �I about a given axis is calculated by integrating the product of the mass element and the square of its distance from the axis of rotation.