What is the quantity of matter that a body contains known as?

The quantity of matter that a body contains is referred to as mass. Mass is a fundamental property of an object and is measured in kilograms (kg). It represents the amount of material or substance within the object, regardless of its location in a gravitational field.

For example, an object's mass remains constant whether it is on Earth, on the Moon, or in outer space. This is different from weight, which is the force exerted by gravity on that mass and can change depending on the gravitational environment. Volume refers to the amount of space an object occupies, while density is the mass per unit volume of an object, which provides insight into how compact the matter is within it. Thus, the concept of mass is central to understanding the fundamental characteristics of matter in physics.