Understanding of basic phenomena connected with electromechanical properties of solid materials. Overview of electromechanical (piezoelectric, ferroelectric, electrostrictive) properties of materials representing different classes of solids (pure piezoelectrics, ferroelectrics, ferroelastics and higher order ferroics, crystals, ceramics, composites, thin films, and so on) and macroscopic description of how their electromechanical features relate to other macroscopic properties.