With this book, appearing in Springer's prestigious series Ergebnisse der Mathematik, Friedman and Morgan give a comprehensive introduction to current research in the field of applications of gauge theory to complex surfaces. Their streamlined modern presentation of this very active area of mathematical research will be very welcome to researchers and graduate students alike. The study is divided into 4 main areas: - Classical complex surface theory; - gauge theory and Donaldson invariants; - deformations of holomorphic vector bundles; - explicit calculations for elliptic surfaces. The book very successfully bridges the two areas of 4-manifold topology and complex surface theory, thus unifying the classical theory of Barth/Peters/van de Ven (ERGEBNISSE 4) with gauge theory techniques described by Donaldson/Kronheimer.