  The primary concern of this thesis is to understand the formation and
properties of the first galaxies, as well as the influence of the first stars
in terms of radiative, mechanical and chemical feedback. In particular, we
elucidate the role of turbulence, ionizing radiation by massive Population III
stars, mechanical feedback by highly energetic supernovae, and chemical
enrichment. In light of the next generation of ground- and space based
telescopes, we derive their observational signature in terms of recombination
radiation, bremsstrahlung and 21 cm emission. We find that the cumulative 21 cm
signal of the first H II regions will likely be observable by the planned SKA,
while the recombination radiation from the first starbursts might be observable
by JWST. These probes are essential to test the theoretical framework of the
first stars and galaxies and shed some light on this elusive period of cosmic
history.
