  Ionic solids and melts are compounds in which the interactions are dominated
by electrostatic effects. However, the polarization of the ions also plays an
important role in many respects as has been clarified in recent years thanks to
the development of realistic polarizable interaction potentials. After
detailing these models, we illustrate the importance of polarization effects on
a series of examples concerning the structural properties, such as the
stabilization of particular crystal structures or the formation of
highly-coordinated multivalent ions in the melts, as well as the dynamic
properties such as the diffusion of ionic species. The effects on the structure
of molten salts interfaces (with vacuum and electrified metal) is also
described. Although most of the results described here concern inorganic
compounds (molten fluorides and chlorides, ionic oxides...), the particular
case of the room-temperature ionic liquids, a special class of molten salts in
which at least one species is organic, will also be briefly discussed to
indicate how the ideas gained from the study of "simple" molten salts are being
transferred to these more complex systems.
