X-ray astronomy has undergone a revolution in recent years. With the launch of two orbiting observatories, Chandra and XMM-Newton, astronomers are now able to obtain spectra and images at a higher resolution than ever before. Observations have had a major impact on topics ranging from protostars to cosmology. The contributions in this 2004 work, by leading authorities in the field, originate from a Royal Society Discussion Meeting that was held to review results from the current generation of X-ray telescopes, and set them in context. This book is a valuable reference for research astronomers and graduate students wishing to understand the latest developments in this exciting field.