Density is a fundamental physical property defined as the ratio of an object's mass to its volume. Quantitatively, it measures how much mass is contained within a specific amount of space, and it is typically calculated using the formula $\text{Density} = \text{Mass} / \text{Volume}$. In the International System of Units (SI), common units for density include kilograms per cubic meter ($\text{kg}/\text{m}^3$). This property is essential in physical science, serving as a key characteristic for identifying substances and predicting behaviors in fluid dynamics. For instance, the concept of density is central to understanding buoyancy, where the ability of an object to float or sink depends on the relationship between the object's density and the density of the surrounding fluid.