  Nonequilibrium phase transitions can be typified in a similar way to
equilibrium systems, for instance, by the use of the order parameter. However,
this characterization hides the irreversible character of the dynamics as well
as its influence on the phase transition properties. Entropy production has
revealed to be an important concept for filling this gap since it vanishes
identically for equilibrium systems and is positive for the nonequilibrium
case. Based on distinct and general arguments, the characterization of phase
transitions in terms of the entropy production is presented. Analysis for
discontinuous and continuous phase transitions has been undertaken by taking
regular and complex topologies within the framework of mean field theory (MFT)
and beyond the MFT. A general description of entropy production portraits for
$Z_2$ (``up-down'') symmetry systems under the MFT is presented. Our main
result is that a given phase transition, whether continuous or discontinuous
has a specific entropy production hallmark. Our predictions are exemplified by
an icon system, perhaps the simplest nonequilibrium model presenting an
order-disorder phase transition and spontaneous symmetry breaking: the majority
vote model. Our work paves the way to a systematic description and
classification of nonequilibrium phase transitions through a key indicator of
system irreversibility.
