What is the relationship between viscosity and density in fluids?

Viscosity and density are related in fluids because viscosity is a measure of a fluid's resistance to flow, while density is a measure of how much mass is packed into a given volume of the fluid. Generally, fluids with higher density tend to have higher viscosity, meaning they are thicker and flow more slowly. Conversely, fluids with lower density typically have lower viscosity and flow more easily.