  In this contributed chapter, I review our current understanding of the
applicability of hydrodynamics to modeling the quark-gluon plasma (QGP),
focusing on the question of hydrodynamization/thermalization of the QGP and the
anisotropic hydrodynamics (aHydro) far-from-equilibrium hydrodynamic framework.
I discuss the existence of far-from-equilibrium hydrodynamic attractors and
methods for determining attractors within different hydrodynamical frameworks.
I also discuss the determination of attractors from exact solutions to the
Boltzmann equation in relaxation time approximation and effective kinetic field
theory applied to quantum chromodynamics. I then present comparisons of the
kinetic attractors with the attractors obtained in standard second-viscous
hydrodynamics frameworks and anisotropic hydrodynamics. I demonstrate that, due
to the resummation of terms to all orders in the inverse Reynolds number, the
anisotropic hydrodynamics framework can describe both the weak- and
strong-interaction limits. I then review the phenomenological application of
anisotropic hydrodynamics to relativistic heavy-ion collisions using both
quasiparticle aHydro and second-order viscous aHydro. The phenomenological
results indicate that aHydro provides a controlled extension of dissipative
relativistic hydrodynamics to the early-time far-from-equilibrium stage of
heavy-ion collisions. This allows one to better describe the data and to
extract the temperature dependence of transport coefficients at much higher
temperatures than linearized second-order viscous hydrodynamics.
