Absolute viscosity, also known as dynamic viscosity, is a measure of a fluid’s internal resistance to flow when subjected to an applied force. It quantifies the friction between fluid layers as they move at different velocities. The higher the absolute viscosity, the more resistant the fluid is to flow. This property is crucial in determining the performance of lubricants, fuels, paints, and other fluids in various industrial and engineering applications. Absolute viscosity is typically measured in units of Pascal-seconds (Pa·s) or poise (P) and is temperature-dependent, meaning it decreases as temperature increases in most fluids.