Based on a meeting organized by ITESRE/CNR and NASA/GSFC, with support from ASI, this book summarizes past discoveries and considers the science challenges of the missions in the first decade of the 21st century. The two subjects of the book are x-ray binaries and AGN, and the x-ray background.

The meeting marked an opportunity to look back on a successful decade of results from the ROSAT, ASCA, RXTE and BeppoSAX missions. The two topics covered at the meeting were: (1) x-ray binaries and (2) AGN and the x-ray background. X-ray binaries provide a natural laboratory for probing the extreme environments of black holes and neutron stars. The meeting was organized jointly by ITESRE/CNR and NASA/GSFC, with support from ASI. The meeting itself proved to be very timely and gave an excellent summary of the past discoveries as well as the science challenges awaiting the new missions that would dominate the first decade of the 21st century.