  Dynamical symmetries are of considerable importance in elucidating the
complex behaviour of strongly interacting systems with many degrees of freedom.
Paradigmatic examples are cooperative phenomena as they arise in phase
transitions, where conformal invariance has led to enormous progress in
equilibrium phase transitions, especially in two dimensions. Non-equilibrium
phase transitions can arise in much larger portions of the parameter space than
equilibrium phase transitions. The state of the art of recent attempts to
generalise conformal invariance to a new generic symmetry, taking into account
the different scaling behaviour of space and time, will be reviewed. Particular
attention will be given to the causality properties as they follow for
co-variant $n$-point functions. These are important for the physical
identification of n-point functions as responses or correlators.
