The book analyzes the thermodynamic aspects of several phenomena induced by flow in fluid systems. It begins with a macroscopic formulation of the thermodynamic theory, within the framework of extended irreversible thermodynamics, and compares it with other non-equilibrium approaches. These macroscopic results are examined from a microscopic point of view for different systems, namely, ideal gases, non-ideal gases and dilute polymer solutions. The thermodynamic approach is applied to the analysis of shear-induced changes in the phase diagram of polymer solutions, to shear-induced diffusion and to chemical reactions under flow. It is also compared with the dynamical approach based on the detailed evolution equations. The book may be especially useful for researchers in non-equilibrium thermodynamics or non-equilibrium statistical mechanics and in polymer physics or materials sciences.