This book is the result of more than 20 years of experience in working with near-infrared spectroscopy for raw milk analysis. The totality of this work presents extensive possibilities for milk spectral measurements that can be carried out in dairy. Moving beyond the standard milk components such as fat, protein, or lactose, this book presents near-infrared spectroscopy as a method that can also be used in disease diagnostics. The measurements and experimental results presented here are all based on the utilization of usually neglected near-infrared regions-regions with strong absorbance of water. The author has found the water - light interaction discussed to be an immensely rich source of information, not only on milk composition but also on the physiological status of the animals involved. A special section of the book is dedicated to exploration of potential interfering factors that may influence the analysis and contribute to the robustness of the models. The research described in this book served as a basis for the development of the novel discipline aquaphotomics and is of interest to anyone working in this field.