  The Kerr/CFT correspondence is a holographic duality between a two
dimensional chiral conformal field theory (CFT) and the very near horizon limit
of an extremal black hole, which includes an AdS2 structure. To understand the
dual chiral CFT2, we apply the Kerr/CFT correspondence to a certain class of
black holes embedded in string theory, which include the D1-D5-P and the BMPV
black holes, and obtain the correct entropies for the black holes
microscopically. These have an AdS3 structure in the near horizon geometry and
an AdS2 structure in the very near horizon geometry. We identified one of the
two Virasoro symmetries in the nonchiral CFT2 dual to the AdS3, i.e. in the
AdS3/CFT2, with the Virasoro symmetry in the chiral CFT2 dual to the AdS2, i.e.
in the Kerr/CFT correspondence. We also discuss a way to understand the chiral
CFT2 dual to generic extremal black holes. A kind of universality for the very
near horizon geometries of extremal black holes will be important for the
validity of the Kerr/CFT correspondence. Based on this analysis, we propose
that the Kerr/CFT correspondence can be understood as a decoupling limit in
which only the ground states remain.
