  The last few years have seen an explosion of interest in hydrodynamic effects
in interacting electron systems in ultra-pure materials. One such material,
graphene, is not only an excellent platform for the experimental realization of
the hydrodynamic flow of electrons, but also allows for a controlled derivation
of the hydrodynamic equations on the basis of kinetic theory. The resulting
hydrodynamic theory of electronic transport in graphene yields quantitative
predictions for experimentally relevant quantities, e.g. viscosity, electrical
conductivity, etc. Here I review recent theoretical advances in the field,
compare the hydrodynamic theory of charge carriers in graphene with
relativistic hydrodynamics and recent experiments, and discuss applications of
hydrodynamic approach to novel materials beyond graphene.
