  We discuss emergence of geometrical scaling as a consequence of the nonlinear
evolution equations of QCD, which generate a new dynamical scale, known as the
saturation momentum: Qs. In the kinematical region where no other energy scales
exist, particle spectra exhibit geometrical scaling (GS), i.e. they depend on
the ratio pT=Qs, and the energy dependence enters solely through the energy
dependence of the saturation momentum. We confront the hypothesis of GS in
different systems with experimental data.
