Density is a fundamental physical property quantifying the mass of a substance relative to its volume. It is determined by dividing the mass of an object or substance by its volume, providing a measure of how tightly packed its particles or molecules are. A higher density signifies a greater mass within a specific volume, indicating a more compact arrangement of particles. This property is instrumental in distinguishing between different materials and holds critical importance in various scientific fields, including physics, chemistry, and engineering. Practically, density impacts how substances behave in different environments; denser materials tend to sink in fluids of lower density, while less dense ones may float. Understanding density is paramount in disciplines like materials science, geology, and fluid dynamics.