  We summarize current developments in the investigation of glassy matter using
nonlinear dielectric spectroscopy. This work also provides a brief introduction
into the phenomenology of the linear dielectric response of glass-forming
materials and discusses the main mechanisms that can give rise to nonlinear
dielectric response in this material class. Here we mainly concentrate on
measurements of the conventional dielectric permittivity at high fields and the
higher-order susceptibilities characterizing the 3-omega and 5-omega components
of the dielectric response as performed in our group. Typical results on
canonical glass-forming liquids and orientationally disordered plastic crystals
are discussed, also treating the special case of supercooled monohydroxy
alcohols.
