The quark-gluon plasma produced in the heavy-ion collisions at RHIC (Brookhaven) is a strongly coupled relativistic fluid. As a result perturbative QCD fails to capture the fundamental properties of this matter. On the other hand, non-perturbative field theory techniques such as the lattice-QCD are not convenient to study the most important real-time observables. I will explain how string theory comes to rescue! Using the idea of gauge-gravity correspondence we construct a gravitational model, designed to capture the basic properties of QCD. I will first explain the phase diagram of the theory and then move onto non-equillibrium domain and derive general properties of the quark-gluon fluid, such as the viscosity parameters and energy loss of heavy-quark probes.