  This is a set of introductory lecture notes on black holes in string theory.
After reviewing some aspects of string theory such as dualities, brane
solutions, supersymmetric and non-extremal intersection rules, we analyze in
detail extremal and non-extremal 5d black holes. We first present the D-brane
counting for extremal black holes. Then we show that 4d and 5d non-extremal
black holes can be mapped to the BTZ black hole (times a compact manifold) by
means of dualities. The validity of these dualities is analyzed in detail. We
present an analysis of the same system in the spirit of the adS/CFT
correspondence. In the ``near-horizon'' limit (which is actually a near
inner-horizon limit for non-extremal black holes) the black hole reduces again
to the BTZ black hole. A state counting is presented in terms of the BTZ black
hole.
