The first part of the book covers the electrolyte solution in its stationary state-electrostatic, and various ion-dipole, dipole-dipole, and mutual repulsion interactions. The second part covers the electrolyte solution in its nonstationary status-electrical 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.