Density plays a crucial role in understanding buoyancy. Density is defined as the mass of an object divided by its volume. It measures how tightly packed the particles of a substance are. When an object is immersed in a fluid, such as water, it experiences an upward buoyant force that is equal to the weight of the fluid displaced by the object.

To better comprehend this concept, let's consider an example. Imagine you have a glass of water and a glass of oil. If you were to drop a small metal cube into each of these fluids, you would observe that the cube sinks in the water but floats in the oil. This is because the densities of the cube, water, and oil are distinct. The cube's density is higher than that of water, causing it to sink. On the other hand, the density of oil is lower than the cube's, resulting in it floating.

Understanding density enables us to analyze and predict the behavior of objects in different fluids. It explains why certain objects float while others sink.