Density is the amount of something in a fixed measurement, such as population per square mile, grams (g) per milliliter (ml), or grams per cubic centimeter.
Here are examples of substances and their density expressed as grams per cubic centimeter.
Density plays many rolls. For example, population density is a way to express how many people are living in a specific area. Density is also a predictor of buoyancy, as something floats in a liquid if it is less dense than the liquid.