  This is an expanded version of a talk given at ``{\em IInd Recontre du
Vietnam}'' held at Ho Chi Minh City in October, 1995. We discuss several
aspects of black hole entropy in string theory. We first explain why the
geometric entropy in two dimensional noncritical string theory is
nonperturbatively finite. We then explain the philosophy of regarding massive
string states as black branes and how the Beckenstein-Hawking entropy for
extremal BPS black holes may be understood as coming from degeneracy of string
states. This is then discussed in the context of D-strings in Type IIB
superstrings. We then describe non-BPS excitations of D-strings and their
entropy and explore the possibility that their decay describes Hawking
radiation. For these D-strings and other D-branes the entropy and temperature
are consequences of the physical motion of stuck open strings along the D-brane
and this leads to a simple space-time interpretation. Finally we speculate that
the horizon may be itself regarded as a D-brane.
