This book differs in several respects from the excellent one by Shapiro and Tcukolsky. The range of topics dealt with in this book is narrower, but in general the topics are treated in greater depth. Also, emphasis is placed here on emerging topics—the many forms in which "neutron" stars may be realized in nature-hyperon stars, hybrids stars with intricate crystalline interiors of quark and nuclear matter, and strange quark stars and dwarfs sheathed in nuclear material. These marvelous objects challenge our understanding of dense-matter physics, both nuclear and particle, not to mention our imagination.