  This brief review summarizes the main experimental discoveries made at RHIC
and then discusses their implications. The robust collective flow phenomena are
well described by ideal hydrodynamics, with the Equation of State (EoS)
predicted by lattice simulations. However the transport properties turned out
to be unexpected, with rescattering cross section one-to-two orders of
magnitude larger than expected from perturbative QCD. These and other
theoretical developments indicate that Quark-Gluon Plasma (QGP) produced at
RHIC, and probably in a wider temperature region $T_c<T<4T_c$, is not at all a
weakly coupled quasiparticle gas, but is rather in a strongly coupled regime,
sQGP for short. After reviewing two other ``strongly coupled systems'', (i) the
strongly coupled supersymmetric theories studied via Maldacena duality; (ii)
trapped ultra-cold atoms with very large scattering length, we return to sQGP
and show that there should exist literally hundreds of bound states in it in
the RHIC domain, most them colored. We then discuss recent ideas of their
effect on the EoS, viscosity and jet quenching.
