  QCD predicts that strongly interacting matter will undergo a transition from
a state of hadronic constituents to a plasma of unbound quarks and gluons. We
first survey the conceptual features of this transition and its description in
finite temperature lattice QCD, before we address its experimental
investigation through high energy nucleus-nucleus collisions. After considering
the conditions achievable in such collisions, we discuss the possible probes to
check if the produced medium in its early stages was indeed deconfined. We then
elaborate the method that has emerged and the results which were obtained using
the most extensively studied deconfinement probe, the suppression of charmonium
production. In closing, we discuss possible supporting information provided
through the study of soft hadronic probes.
