Biophotonics and Biosensing brings together the knowledge of the basic principles of the field of light–biological tissue interaction, detection methods, data processing techniques, and research, diagnostic, and clinical applications. It is suitable for new entrants to the field, while also highlighting the latest developments for experts. This volume includes perspectives by leading experts from the biophotonics and biosensing, biomedical engineering, and data science communities. The book provides a basic grounding in the key theoretical principles and practical components of biophotonics and biosensing. Working principles of devices used in spectroscopy, microscopy, and optical sensing are presented, along with their application domains. The reader will learn about existing microscopy-based techniques used in biomedical applications for diagnosis and get to know different signal- and image-processing algorithms, including the state of the art in artificial intelligence approaches, as used in biophotonics. Finally, the book describes through concrete examples, including sample preparation and measurement approaches, how the field has developed, thanks to the integration of biophotonics and optical biosensing with advanced signal and image-processing.