What does mass measure in an object?

Mass measures the amount of matter contained in an object. It directly relates to the number of particles that make up the object, irrespective of its volume or the gravitational force acting upon it. While volume pertains to the space an object occupies, weight is the force experienced by an object due to gravity, which can vary based on location. Density, on the other hand, defines the mass of an object per unit of volume and is a property derived from both mass and volume. Thus, mass is most accurately associated with measuring matter itself.