The field of ferroelectricity has greatly expanded and changed in recent times. In addition to classical organic and inorganic ferroelectrics, new fields and materials, unknown or inactive 20 to 40 years ago, have appeared. They are important for both basic science and applications, and show technological promise for novel multifunctional devices. New fields include multiferroic magnetoelectric systems, where spontaneous polarization and spontaneous magnetization are allowed to coexist; incommensurate ferroelectrics, where the periodicity of the order parameter is incommensurate to the...