Welcome to the proceedings of the Fifth International Workshop on Digital Watermarking (IWDW). Since the first IWDW held in Seoul, Korea in 2002, it has been a focal point for meeting in person and disseminating valuable scientific and technological developments in watermarking. IWDW 2006 was held on Jeju, the dream island in Korea. The main theme of the workshop was Meet the Challenges in this Digital World As we all know, digital watermarking and its related technologies have emerged as the key ingredients of this digital world. We report on new developments and discuss how to best utilize...