This document discusses laminar and turbulent fluid flow in pipes. It defines laminar flow as smooth, ordered motion of fluid layers and turbulent flow as irregular motion with velocity fluctuations. The Reynolds number determines the flow regime, with laminar flow below 2000 and turbulent flow above 4000. For fully developed laminar pipe flow, the velocity profile is parabolic and the pressure drop is proportional to flow rate, pipe length, and fluid viscosity, inversely proportional to pipe diameter raised to the fourth power.