Extracting the properties of strongly-interacting plasmas from RHIC data

Spectacular measurements over a decade at the Relativistic Heavy Ion Collider (RHIC) indicate remarkable properties for hot and dense nuclear matter in the temperature range $T \sim 200-400$~MeV. For example, shear viscosity appears to be very low, close to universal ``minimum viscosity'' bounds based on quantum arguments. Moreover, the matter is surprisingly opaque even to heavy quarks. These findings led to the emergence of the strongly-interacting quark-gluon plasma (sQGP) paradigm. In this talk I will review the current status of determination of key bulk matter properties from RHIC heavy-ion data, and discuss remaining theoretical challenges.