  This review article describes major advances associated with the Dicke model,
starting in the 1950s when it was introduced to explain the transition from a
normal to a superradiant phase. Since then, this spin-boson interacting model
has raised significant theoretical and experimental interest in various
contexts. The present review focuses on the isolated version of the model and
covers properties and phenomena that are better understood when seen from both
the classical and quantum perspectives, in particular, the onset of chaos,
localization, and scarring.
