  At high temperatures, strongly interacting matter becomes a plasma of
deconfined quarks and gluons. In statistical QCD, deconfinement and the
properties of the resulting quark-gluon plasma can be investigated by studying
the in-medium behaviour of heavy quark bound states. In high energy nuclear
interactions, quarkonia probe different aspects of the medium formed in the
collision. So, we first reviewed the fate of quarkonia in the different stages
of the (dynamical) system produced at the collision. We have then presented our
present work on the dissociation of the heavy quarkonium states in a hot QCD
medium by investigating the medium modifications to heavy quark potential. In
contrast to the usual screening picture, interestingly our theory gives rise
the screening of the charge, not the range of the potential.
