  We show how the investigation of the redshifted 21-cm radiation can give
insight into the development of structures in the early universe (at redshifts
z>5). In particular we investigate: the epoch of the first light; the
fluctuations in the redshifted 21-cm emission induced by the density
inhomogeneities in CDM dominated universes; the emission and absorption shells
that are generated around the first bright quasars. Such features can be
observed with the next generation radio facilities.
