[en] We survey the thermodynamics of strongly interacting matter, as predicted by quantum chromodynamics. At low values of temperature and density, we find hadronic matter, while at high values the system becomes a primordial plasma of non-interacting massless quarks and gluons. Separating the two regimes is a transition region in which colour deconfinement and chiral symmetry restoration take place. We obtain preliminary values for the transition parameters and discuss the possibility of observing plasma formation in high energy heavy ion collisions. (orig.)