  This article gives a brief overview of some recent advances in our
understanding of the physics of dense strongly interacting matter, from
measurements done at the CERN SPS. The presently available results are very
interesting, and are likely to reflect the production of a new state of matter
in central Pb-Pb collisions, at the highest SPS energies. However, important
questions require further work. Particular emphasis is given to developments
made since the Quark Matter 1999 conference, and to issues that justify the
continuation of the SPS heavy ion physics program beyond year 2000.
