  We clarify the relation between gravitational entropy and the area of
horizons. We first show that the entropy of an extreme Reissner-Nordstr\"om
black hole is $zero$, despite the fact that its horizon has nonzero area. Next,
we consider the pair creation of extremal and nonextremal black holes. It is
shown that the action which governs the rate of this pair creation is directly
related to the area of the acceleration horizon and (in the nonextremal case)
the area of the black hole event horizon. This provides a simple explanation of
the result that the rate of pair creation of non-extreme black holes is
enhanced by precisely the black hole entropy. Finally, we discuss black hole
$annihilation$, and argue that Planck scale remnants are not sufficient to
preserve unitarity in quantum gravity.
