  We review the status of particle interferometry in ultra-relativistic
nucleus-nucleus collisions. The theoretical focus is on the model-independent
space-time interpretation of HBT radius parameters and its extension to the
geometrical and dynamical asymmetries generated in finite impact parameter
collisions. On the experimental side, we give a complete account of all
presently available data for beam energies above 2 AGeV. We discuss what these
data imply for the dynamics and space-time extension of the collision region
and for the condition under which particles decouple from this region.
