Cancer metastasis is one of the greatest challenges for our society and is responsible for over 90% of cancer-related deaths. Even in the 21st century, currently available therapies have very limited curative effects for metastatic cancers patients, where the five-year survival rate is only about 20%. Our society needs rapid, sensitive, and reliable cancer therapy which will help save millions of lives every year worldwide. There is no doubt that the development of nano-material based targeted therapy techniques are fast growing research areas for oncology, nanomedicine, chemistry, biology, biomedical engineering and other disciplines. Photo-thermal therapy is a minimally-invasive targeted therapy using bio-conjugated nanoparticles, in which photon energy is converted into heat to kill cancer. Over the last ten years, society has experienced a tremendous growth in the development and implementation of photothermal therapy for cancer. To summarize the recent growth, the first volume in the Photothermal Therapy: Mechanisms, Efficiency and Future Directions series discusses the development of different nanomaterial based photothermal therapy, which have the capability for targeted therapy using near infrared (NIR) light. It contains six chapters written by renowned experts in this area, covering from basic science to possible device design which can have immense applications in our society. This book is unique in its design and content, providing an in depth analysis of this scientific field to elucidate molecular mechanisms of photothermal therapy, engineering design for targeted therapy and the latest research on evolving therapeutic technology to tackle the challenges society is facing now due to cancer and other diseases. The readers will be very pleased to read the wide range of state-of-the-art targeted therapeutic techniques, which have been developed for targeted photo-therapy of cancer, drug resistance bacteria and viruses.