The first part of the book covers the electrolyte solution in its stationary stateelectrostatic, and various ion-dipole, dipole-dipole, and mutual repulsion interactions. The second part covers the electrolyte solution in its nonstationary statuselectrical conductivity, viscosity, and diffusion. This theoretical framework allows for the determination of activity coefficients of concentrated electrolyte solutions, which play a key role in many aspects of electrochemistry and for developing novel advanced processes in inorganic chemical plants.