  The two arguably most generic phenomena seen in ultra-relativistic heavy ion
collisions are the flow of essentially all soft hadronic observables and the
quenching of essentially all hard hadronic observables. Limiting the discussion
to these two classes of phenomena, I review what can be said so far about the
properties of hot and dense QCD matter from the heavy ion programs at RHIC and
at the LHC, and I discuss the opportunities for further progress in the coming
years.
