Photoacoustic imaging (also called optoacoustic imaging) is a hybrid modality based on the generation and detection of ultrasound in response to optical absorption of tissue. It combines advantages from both optical and ultrasound imaging, providing functional, molecular and microstructural information of tissue at scalable spatial resolution and depth. This technology has undergone exponential growth over the last two decades, and it is now widely viewed as one of the most exciting biomedical imaging modalities. This book introduces the technology and applications with chapters written by leading international research groups. It will be of interest to a wide range of audiences, including postgraduate students and researchers in physics and engineering as well as biomedical and clinical sciences. Chapters 8, 16, 17 and 21 are available open access under a Creative Commons Attribution 4.0 International License via link.springer.com.