Density is a physical value that compares the amount of matter that a body has with its volume. Such density determines the relation of these two values, for example, the body with a lot of matter in a given volume has a high density. The density formula is given as <em>mass divided by volume</em>, and is usually expressed in grams per cubic centimeter. It should be emphasized that the density is expressed as the number of particles per unit volume, not the density of the particle itself.