In a qualitative way, the tendency of undisturbed objects to stay at rest or to keep moving with the same velocity is called inertia.Example 1: We tend to remain at rest with respect to the seat until the driver applies a braking force to stop the motorcar due to the inertia of motion.Example2: The dust particles fly away from the blanket when we jerk it due to the inertia of rest.
If an object in motion then it will wants remain in motion and its natural tedency , that it regist to change its state