Q.  What is inertia?

Ans. It says that a body tries to remain or continues in its state of motion or rest until and unless an external force is applied to stop it or move it.

And that force should be equal or more than that of the force exerted by the object.

So basically inertia has a major role in human life.
Like while you are in a bus inertia plays a major role.
Even if in sports too inertia has its role to be played.
In the turnings while you drive a car.
etc....