  We discuss the afterglows from the evolution of both spherical and
anisotropic fireballs decelerating in an inhomogeneous external medium. We
consider both the radiative and adiabatic evolution regimes, and analyze the
physical conditions under which these regimes can be used. Afterglows may be
expected to differ widely among themselves, depending on the angular anisotropy
of the fireball and the properties of the environment. They may be entirely
absent, or may be detected without a corresponding $\gamma$-ray event. A
tabulation of different representative light curves is presented, covering a
wide range of behaviors that resemble what is currently observed in GRB 970228,
GRB 970508 and other objects.
