  Liquid crystals have attracted enormous interest because of the variety of
their phases and richness of their application. The interplay of general
physical symmetries and specific molecular features generates a myriad of
different phenomena. A surprising behavior of liquid crystals is the reentrancy
of phases as temperature, pressure, or concentration are varied. Here, we
review the main experimental facts and the different theoretical scenarios that
have guided the understanding of bulk reentrant nematics. Recently, some
computer simulations of a system confined to nanoscopic scales have found new
dynamical features of the reentrant nematic phase. We discuss this prediction
in relation with the available experimental evidence on reentrant nematics and
with the dynamics of liquids in strongly confined environments.
