  The "unreasonable effectiveness" of relativistic fluid dynamics in describing
high energy heavy-ion and even proton-proton collisions are demonstrated and
discussed. Several recent ideas of optimizing relativistic fluid dynamics for
the specific challenges posed by such collisions will be presented, and some
thoughts will be offered why the framework works better than originally
expected. I will also address the unresolved question where exactly
hydrodynamics breaks down, and why.
