  Inverse patchy colloids are nano- to micro-scale particles with a surface
divided into differently charged regions. This class of colloids combines
directional, selective bonding with a relatively simple particle design: owing
to the competitive interplay between the orientation-dependent attraction and
repulsion -- induced by the interactions between like/oppositely charged areas
-- experimentally accessible surface patterns are complex enough to favor the
stabilization of specific structures of interest. Most important, the behavior
of heterogeneously charged units can be ideally controlled by means of external
parameters, such as the pH and the salt concentration. We present a concise
review about this class of systems, spanning the range from the synthesis of
model inverse patchy particles to their self-assembly, covering their
coarse-grained modeling and the related numerical/analytical treatments.
