  I review some important results from RHIC experiments. They were obtained in
a unique environment for studying QCD bulk matter at temperatures and densities
that surpass the limits where hadrons can exist as individual entities, raising
the quark-gluon degrees of freedom to prominence. These findings support the
major experimental observations from measuring the bulk properties of particle
production, particle ratios and chemical freeze-out conditions, elliptic flow
followed by hard probes measurements: di-jet fragment azimuthal correlations,
high-pt hadron suppression, and heavy-flavors probes. I present the
measurements as a function of collision centrality, energy, system size and for
different particle species. These results reveal that a dense strongly
interacting medium was created in central Au+Au collisions at 200 GeV: the RHIC
discovery. Further, they suggest that this medium is partonic. However, the
discoveries so far observed at RHIC are far from being understood fully.
Accordingly, the focus of the experiments has shifted from the discovery phase
to the detailed exploration phase of the properties of this medium.
