  These notes are based on lectures given at the Erwin-Schrodinger Insitut in
Vienna in 2006/07 and at the 2007 School on Attractor Mechanism in Frascati.
Lecture I: special geometry from the superconformal point of view. Lecture II:
black hole attractor mechanism, its underlying variational principle, and black
hole partition functions. Lecture III: large and small BPS black holes in N=4
supergravity. Lecture IV: state counting for N=4 string compactifications.
Appendix A: special geometry from the mathematical point of view. Appendix B:
review of modular forms. Contains four problems which allow the readers to
develop some of the key concepts by themselves.
