The first aim of this book is to present all techniques devoted to non-invasive normal or diseased skin measurement. As opposed to current books which present novel methods of investigating the skin, it embraces old and new validated techniques, for all skin suborgans and functions. Thus it may be consulted as a small encyclopedia since it provides the answer to any question concerning skin measurement. Each technique is discussed to help select the most appropriate one for each special case. Within each chapter, the meaning of the obtained parameters is highlighted so that the user is able to interpret the results correctly. The second aim of the book is to base the skin investigation on the physiology and anatomy. Each chapter is preceded by a compendium of current knowledge on the structure or function dealt with. Accordingly, this book is also a manual of skin physiology (21 chapters). There is no recent book on skin physiology - most other books deal with molecular biology. However, the molecular level seems too narrow - the dermatologist, cosmetician, and researcher often need this information on skin physiology as well. Furthermore, the information on the physiology at organ level is essential for understanding in vivo non-invasive investigations of skin. A third aim of the book is to provide help for research purposes. This book consists of a collection of quantity of numerical data on skin anatomy and physiology. It contains a novel, and presently unique list of more than 400 physical and biological skin constants, either dimensional or functional, which are all referenced. In addition, this book is also very attractive to clinical dermatologists as some chapters contain valuable maps and are devoted to clinical scoring of current skin diseases. In summary, this book is a resource for all those interested in or already dealing with the skin. It is an expanded and updated version of a French book published in 2000.