  Gamma-Ray Bursts (GRBs) are unique probes of the cosmic star formation
history and the state of the intergalactic medium up to the redshifts of the
first stars. In particular, the ongoing {\it Swift} mission might be the first
observatory to detect individual Population~III stars, provided that the
massive, metal-free stars were able to trigger GRBs. {\it Swift} will
empirically constrain the redshift at which Population~III star formation was
terminated, thus providing crucial input to models of cosmic reionization and
metal enrichment.
