Density is a word we use to describe how much space an object or substance takes up (its volume) in relation to the amount of matter in that object or substance (its mass). Another way to put it is that density is the amount of mass per unit of volume. If an object is heavy and compact, it has a high density.

What does the density means?

1 : the quantity per unit volume, unit area, or unit length: as. a : the mass of a substance per unit volume. b : the distribution of a quantity (as mass, electricity, or energy) per unit usually of space. c : the average number of individuals or units per space unit a population density of 500 per square mile.

What density tells us?

Density tells scientists how "heavy" a substance is. If a substance has a higher density, it is heavier. Likewise a lighter density means it is much lighter. For example, air has a density of approximately 1.225kgm3 .