The quantity of matter that an object contains is called its mass.
Mass is a fundamental property of physical objects; it is a measure of the amount of matter in an object and is typically measured in kilograms or grams. Unlike weight, which can change depending on the gravitational pull acting on the object, the mass of an object remains constant regardless of its location in the universe. In everyday terms, mass can be thought of as a way to quantify how much ‘stuff’ is in something, and it plays a crucial role in physics, particularly in concepts relating to inertia and energy.