What is density exactly?

DENSITY is a physical property of matter, as each element and compound has a unique density associated with it. Density defined in a qualitative manner as the measure of the relative "heaviness" of objects with a constant volume.

For example: A rock is obviously more dense than a crumpled piece of paper of the same size.
A styrofoam cup is less dense than a ceramic cup.

Density may also refer to how closely "packed" or "crowded" the material appears to be - again refer to the styrofoam vs. ceramic cup.

Density can also be defines as,

• Density is the mass per unit volume. This means that thedensity of any solid, liquid or gas can be found by dividing its mass in kilograms by its volume in cubic metres.Density can be found using the equation: The unit fordensity is kg m

Formula for calculating density,
D =mass/volume