Non-equilibrium thermodynamics is a branch of physics that studies the behavior of macroscopic systems that are not in a state of thermodynamic equilibrium. It investigates irreversible processes, transport phenomena such as heat conduction, diffusion, and viscous flow, and the production of entropy driven by spatial or temporal gradients of thermodynamic variables. This field is essential for understanding the dynamic evolution and energy transformations in real-world systems, particularly those far from equilibrium.