The proceedings of the conference Supernovae 2003 (IAU colloquium 192) provides an extensive state-of-the-art survey of all theoretical and observational aspects of supernovae and gamma-ray bursts, as well as their impact on cosmology. This volume offers everyone working in this field an authoritative and comprehensive source of reference. The present volume includes a CD-ROM with the printed proceedings plus poster descriptions and meeting photographs not printed in the book.