In the context of motion, what is inertia best described as?

Inertia is best described as the tendency of an object to maintain its current state of motion, whether that state is at rest or moving at a constant velocity. This concept stems from Newton's First Law of Motion, which states that an object will remain at rest or continue moving in a straight line at constant speed unless acted upon by a net external force. Essentially, inertia is a property that is directly related to the mass of an object; greater mass results in greater inertia, meaning the object resists changes to its state of motion more effectively.

Because of this principle, if there are no forces acting on an object, it will either stay still if it is at rest or keep moving in a straight line if it is already in motion. This understanding of inertia is fundamental in the study of physics, particularly in understanding how objects respond to forces and accelerate.