Inertia

Inertia is the measure of an object's resistance to change. The greater the resistance the greater the inertia and the greater the mass.

The idea of inertia was first presented by Galileo but was truly developed in Newton's First Law of Motion.

Newton's First Law of Motion states:

If an object is at rest it will remain at rest unless acted on by an
outside force. But, if the object is in motion it will stay in motion,
in a straight path, unless acted on by an outside force.