The mass of a physical object is:

The mass of a physical object refers to the amount of matter it contains. It is a fundamental property of an object and is commonly measured in units such as kilograms (kg) or grams (g). The mass of an object remains constant regardless of its location in the universe, meaning it is an intrinsic property of the object itself.

The mass of an object determines its inertia, which is its resistance to changes in motion. Objects with larger masses require more force to accelerate or decelerate compared to objects with smaller masses. Mass is also a factor in determining the gravitational force experienced by an object, as described by Newton's law of universal gravitation.

It's important to note that mass should not be confused with weight. Weight is the force exerted on an object due to gravity and depends on the mass of the object as well as the gravitational field strength. On Earth, weight is often expressed in units of force such as newtons (N) or pounds (lb), while mass is expressed in units of mass such as kilograms (kg) or grams (g).