The book is prepared for students and teachers, also for professionals, in university careers, it is composed of different chapters that deal with the following topics: nature of fluids, kinematics of fluid flow, conservation equations, incompressible flow in pipes and channels, frictional losses in pipeline elements, multiphase flow, fluid distribution, fluid mixing, and beds of solids. Rheology is the discipline of fluid mechanics which studies this relationship. One goal of rheology is to obtain constitutive equations by which stresses may be computed from deformation rates. Fluids without any solidlike elastic behavior do not undergo any reverse deformation when shear stress is removed, and are called purely viscous fluids. The shear stress depends only on the rate of deformation, and not on the extent of deformation (strain). Those which exhibit both viscous and elastic properties are called viscoelastic fluids.