  I review recent measurements of a large set of flow observables associated
with event-shape fluctuations and collective expansion in heavy ion collisions.
First, these flow observables are classified and experiment methods are
introduced. The experimental results for each type of observables are then
presented and compared to theoretical calculations. A coherent picture of
initial condition and collective flow based on linear and non-linear
hydrodynamic responses is derived, which qualitatively describe most
experimental results. I discuss new types of fluctuation measurements that can
further our understanding of the event-shape fluctuations and collective
expansion dynamics.
