Explain moment of inertia

Moment of inertia is the term used to calculate or quantify the amount of mass located at an object's extremities. For instance if all the mass of an object was located in a small compact size (like a lead ball) its moment of inertia would be small compared to the similar amount of mass shaped into a dumbbell. Because a dumbbell has most of its mass located farther from its center. But there is a "qualification" here. Moment of inertia is measured relative to a hypothetical spin axis. Once you choose the spin axis then you measure the moment of inertia by multiplying the mass times its distance to the spin axis squared; I = MR²