Saturation of gluon distribution is a consequence of the non-linear evolution equations of QCD. Saturation implies the existence of the so-called saturation momentum which is defined as a gluon density per unit rapidity per transverse area. At large energies, for certain kinematical domains, saturation momentum is the only scale for physical processes. As a consequence, different observables exhibit geometrical scaling (GS). We discuss a number of examples of GS in different reactions.