  Turbulence is characterized by a large number of degrees of freedom,
distributed over several length scales, that result into a disordered state of
a fluid. The field of quantum turbulence deals with the manifestation of
turbulence in quantum fluids, such as liquid helium and ultracold gases. We
review, from both experimental and theoretical points of view, advances in
quantum turbulence focusing on atomic Bose-Einstein condensates. We also
explore the similarities and differences between quantum and classical
turbulence. Lastly, we present challenges and possible directions for the
field. We summarize questions that are being asked in recent works, which need
to be answered in order to understand fundamental properties of quantum
turbulence, and we provide some possible ways of investigating them.
