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How are inertial mass and gravitational mass related?

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gravitational lens — gravity A galactic cluster, about five billion light-years away, produces a tremendous gravitational field that “bends” light around it. This lens produces multiple copies of a blue galaxy about twice as distant. Four images are visible in a circle surrounding the lens; a fifth is visible near the center of the picture, which was taken by the Hubble Space Telescope.

In physics, inertial mass and gravitational mass are considered equivalent, a concept central to the principle of equivalence.12

Inertial mass is a measure of an object's resistance to acceleration when subjected to any type of force.3
Gravitational mass is determined by the strength of the gravitational force an object experiences when placed within a gravitational field.3

The equivalence principle asserts that these two forms of mass are identical. This means that all objects, regardless of their composition, accelerate at the same rate in a gravitational field. This fundamental relationship was confirmed to high precision through experiments by the Hungarian physicist Roland, Baron von Eötvös, who used a torsion balance to demonstrate that the ratio of gravitational to inertial mass is the same for different substances.1234

This equivalence serves as a cornerstone of Albert Einstein’s general theory of relativity, which describes gravitation as a geometric property of space-time rather than a traditional force.32