Inertia is the tendency of an object to resist changes in its motion. This means that:

* An object at rest will stay at rest unless acted upon by a net force.

* An object in motion will stay in motion at a constant velocity unless acted upon by a net force.

Therefore, inertia is an inherent property of all objects, regardless of their state of motion.

Think of it this way:

* A heavy rock sitting still on the ground has inertia. It takes force to get it moving.

* A car moving at a constant speed on a straight road also has inertia. It takes force to stop it, speed it up, or change its direction.

So, even objects at rest possess inertia. They resist changes in their state of motion, which is why they remain at rest.