  Gluon distributions of colliding hadrons saturate as a result of the
non-linear evolution equations of QCD. As a consequence there exists the so
called saturation momentum, which is related to the gluon density per unit
rapidity per transverse area. When saturation momentum is the only scale for
physical processes, different observables exhibit geometrical scaling (GS). We
show a number of examples of GS and its violation in different reactions.
