Gravitational and inertial mass

Gravitational mass relates to the intensity of an object’s gravitational field required for a given distance, whereas inertial mass is defined by the resistance to change in velocity. Through careful measurements, these two kinds of mass were found to be identical. This led to a new way of looking at gravity.
 Roland Eötvös Hungary 1890 Gravitational and inertial mass

Gravitational mass relates to the intensity of an object’s gravitational field required for a given distance, whereas inertial mass is defined by the resistance to change in velocity. Through careful measurements, these two kinds of mass were found to be identical. This led to a new way of looking at gravity.