  This paper reviews the field of gamma-ray astronomy and describes future
experiments and prospects for advances in fundamental physics and high-energy
astrophysics through gamma-ray measurements. We concentrate on recent progress
in the understanding of active galaxies, and the use of these sources as probes
of intergalactic space. We also describe prospects for future experiments in a
number of areas of fundamental physics, including: searches for an annihilation
line from neutralino dark matter, understanding the energetics of supermassive
black holes, using AGNs as cosmological probes of the primordial radiation
fields, constraints on quantum gravity, detection of a new spectral component
from GRBs, and the prospects for detecting primordial black holes.

Astrophysics