Density, represented by the symbol ρ, is a measure of how much mass is contained in a given volume. It is calculated by dividing the mass of an object by its volume, typically expressed in units like grams per cubic centimeter (g/cm³) or kilograms per cubic meter (kg/m³). Higher density means more mass in a smaller space, while lower density indicates less mass in the same volume. Density plays a crucial role in various scientific fields, including physics, chemistry, and engineering. It helps determine whether an object will float or sink in a fluid, as seen in the principles of buoyancy. Understanding density is essential for material selection and design in many applications.