  Gamma-ray burst astronomy has undergone a revolution in the last three years,
spurred by the discovery of fading long-wavelength counterparts. We now know
that at least the long duration GRBs lie at cosmological distances with
estimated electromagnetic energy release of 10**51 -- 10**53 erg, making these
the brightest explosions in the Universe. In this article we review the current
observational state, beginning with the statistics of X-ray, optical, and radio
afterglow detections. We then discuss the insights these observations have
given to the progenitor population, the energetics of the GRB events, and the
physics of the afterglow emission. We focus particular attention on the
evidence linking GRBs to the explosion of massive stars. Throughout, we
identify remaining puzzles and uncertainties, and emphasize promising
observational tools for addressing them. The imminent launch of HETE-2 and the
increasingly sophisticated and coordinated ground-based and space-based
observations have primed this field for fantastic growth.
