  Together with the CMB, the three sources of information that astronomers have
at high redshift as probes of the formation and evolution of the LSS are QSOs,
galaxies and absorbers observed in the spectrum of distant background objects.
In this contribution I try to give a hint of historical perspective, following
how the technological advances have driven the emphasis from one class to
another, in order to show what are the likely forthcoming milestones.
