Entropy production

Summary

Entropy production is the entropy created inside a system by irreversible processes, as opposed to entropy carried in or out across its boundary. The second law of thermodynamics says that it is never negative, and that it is zero exactly for reversible processes. In a continuous medium it has a local density, which is a sum of products of fluxes and thermodynamic forces. It measures how far a process is from reversibility and how much useful work is lost.