  We give a pedagogical review of relativistic hydrodynamics relevant to
relativistic heavy ion collisions. Topics discussed include linear response
theory derivation of 2nd order viscous hydrodynamics including the Kubo
formulas, kinetic theory derivation of 2nd order viscous hydrodynamics,
anisotropic hydrodynamics and a brief review of numerical algorithms. Emphasis
is given to the theory of hydrodynamics rather than phenomenology.
