Linked from
The 10 pages that link to Dynamic viscosity, each with the reason it gives.
Stokes' lawRelated: The drag increases linearly with this property.
Kinematic viscosityRelated: Dividing this quantity by density produces kinematic viscosity.
Shear rateRelated: It connects shear rate to shear stress for a Newtonian fluid.
Hagen–Poiseuille equationRelated: Flow rate is inversely proportional to this property.