The black hole is one of the the most intriguing objects in our
universe. Although its classical properties are well understood, its
quantum, microscopic nature is poorly understood. String theory has
been successful in explaining certain quantum aspects of black holes,
but there still remain many unresolved problems. In this talk, I will
first review the studies of black holes in string theory, in particular
recent developments about what microscopic structure may be underlying
macroscopic black holes. Then, I will discuss more recent developments
in realizing black hole microstates in the framework of supergravity
and string theory generalization thereof, as non-trivial configurations
of string theory objects.