What is the property of inertia?

Inertia is the property of the body to maintain its state.
The measure of inertia for translational motion is the mass of the body m, for rotational motion the moment of inertia I.
The more body weight, the more difficult it is to change its state.
Example: A passenger car is easier to stop than a commercial vehicle. The mass of a truck is greater than that of a passenger car, the inertia of a truck is greater than that of a passenger car.
With a sharp braking of the bus, passengers continue to move forward by inertia.