  In this article, we briefly review the recent progress on collective flow and
hydrodynamics in large and small systems at the Large Hadron Collider (LHC),
which includes the following topics: extracting the QGP viscosity from the flow
data, initial state fluctuations and final state correlations in 2.76 A TeV
Pb--Pb collisions, correlations and collective flow in high energy p--Pb and
p--p collisions.
