Ion solvation and ion association are the dominant features of electrolyte solutions, with implicationsin areas ranging from biology and geochemistry to technical applications. The physicochemicalproperties of such systems are governed by a delicate balance of solute-solute, solute-solventand solvent-solvent interactions which is still not fully understood despite intensive research formore than 100 years. A major reason for that is the lack of experimental techniques that can characterizemultistep ion-association equilibria, especially of weak aggregates, and provide direct informationon solvation-shell dynamics.Focusing on aqueous electrolyte systems, I would like to show what kind of information can beprovided by dielectric relaxation spectroscopy (DRS) for solution chemistry and physics. After ashort introduction into the scope and principles of DRS, the investigation of ion association equilibriaand the problems associated with weak ion pairing will be discussed. Finally, we focus on waterrelaxation and how this is modified by the electrolyte. It is shown that not only H2O moleculesclose to the solute are affected but also the dynamics and structure of the remaining bulk water. Thehydration mechanisms for hydrophilic and hydrophobic solutes and their manifestation in the observeddielectric behavior will be discussed.