Digital Watermarking is a developing field of research which stands for embedding a signature signal, called 'watermark', into a digital cover, in order to prove ownership, check authenticity or integrity of the cover, and apart from images it may relate to audio, video or even text. In data hiding the medium-carrier is of no importance, and its purpose is restricted in transmitting a secret message through a communication channel without being noticed. Data hiding and digital watermarking are two close but distinct fields which are characterized by data embedding in digital media and sometimes share common characteristics and algorithms. An overview of digital watermarking domain is presented in the first chapter while the rest of the book is dedicated to advanced algorithms and techniques for watermarking and data hiding. This book is ideal for post graduate students who are interested in specializing in digital watermarking and data hiding fields, as well as for pre graduate students who wish to take their first steps in watermarking. Researchers of the field will also find interest in the latest algorithms which achieve increased robustness with minimum image distortion.