  In this talk the status and open questions of the phenomenological
description of all the stages of a heavy ion reaction are highlighted. Special
emphasis is put on event-by-event fluctuations and associated observables. The
first part is concentrated on high RHIC and LHC energies and the second part
reviews the challenges for modeling heavy ion reactions at lower beam energies
in a more realistic fashion. Overall, the main conclusion is that sophisticated
theoretical dynamical approaches that describe many observables in the same
framework are essential for the quantitative understanding of the properties of
hot and dense nuclear matter.
