  Near-infrared surveys provide one of the best opportunities to investigate
the cosmic evolution of galaxies and their mass assembly. We briefly review the
main results obtained so far with the K20 and other recent near-IR surveys on
the redshift distribution, the evolution of the luminosity function and
luminosity density, the nature of old and dusty EROs, the evolution of the
galaxy stellar mass function, the properties of the galaxies in the ``redshift
desert'' and the nature of luminous starbursts at z~2.
