What is density with an example?

Hint: In order to solve this question we need to understand the definition of mass and volume. Mass is defined as weight of the body divided by acceleration due to gravity. Like every matter has some mass. Volume is the space enclosed by an object in three dimensions. Mass is the inherent property of all the objects in the universe, it tells us about how much matter is present in that particular object.

Complete answer:
Density is defined as the number of quantities per unit volume. It can be of various types and depends on situations like mass density is defined as mass per unit volume, number density is defined as number of given substances per unit volume or at micro level density of state is defined as number of particles per unit energy states.

Let us take an example. Let mass “m kg” is distributed in volume “V” so a density is defined as $\rho = \dfrac{m}{V}$ and its SI unit is $kg{m^{ - 3}}$. Density tells us about how densely the matter is situated in the given volume of space.For example The density of water is $1000\,Kg{m^{ - 3}}$.

Note: It should be remembered that density can be real useful quantity in real life as with knowledge of this we can decide which quantity would float on surface of water as the objects having density less than that of water they will float on surface of water whereas objects having density greater than that of water, they will sink inside the water. Also the SI unit of mass density is $kg{m^{ - 3}}$ and the CGS unit is $gc{m^{ - 3}}$.