Noninvasive methods are gaining increasingly in influence and acceptance. This is also true in the field of dermatology, where it is no longer necessary to take biopsies in order to make statements, e.g., on the size of a skin tumor, on the epidermal water content, on the elasticity of the skin. Peter Frosch and Albert M. Kligman have managed to bring together international authors for the first time in one book, each of them a master of "his" investigation method.