Skin physiology assessment is moving from a descriptive approach to a deeper understanding of biophysical and biochemical processes in the stratum corneum, such as epidermal barrier function and stratum corneum hydration. New, non-invasive approaches offer reliable and reproducible methods for product testing in the pharmaceutical and cosmetic industry, as well as in basic research. While standard instruments focus on functional aspects, innovative devices offer a deeper understanding of underlying mechanisms.This book discusses the assessment of skin physiology and of skin functions in clinical studies using non-invasive biophysical instruments, offering readers a comprehensive guide to planning, performing and evaluating the results of scientific studies in skin measurement and the legal framework for these studies. Written by leading experts in the field, it focuses on practical aspects of non-invasive measurements. After introducing the legal aspects of the current framework for clinical cosmetic studies and basic research in cosmetology, it explores the technical practicalities of organizing a testing lab and the pre-requirements for planning a study. The third and main section addresses specific topics in cosmetic testing e.g. skin hydration, and also includes chapters on sensory aspects and in vivo skin structure vizualization. This new, updated edition of Practical Aspects of Cosmetic Testing is a valuable tool for researchers, students, and medical staff wanting to gain insights into how best to assess skin functions in controlled studies using non-invasive biophysical instruments.