The stimulation of the immune system through artificial means for the treatment of cancer is known as cancer immunotherapy. It boosts the ability of the immune system to fight cancer cells. It is a subspecialty within oncology. The antibody proteins belonging to the immune system are able to detect the tumor antigens and bind with them. Immunotherapy can be broadly divided into two types, namely, passive immunotherapy and active immunotherapy. The tumor cells are specifically targeted through the immune system in active immunotherapy. Within passive immunotherapy, the cancer cells are not directly attacked by the immunotherapy, but the ability of the immune system to attack cancer cells is enhanced. This book includes some of the vital pieces of work being conducted across the world, on various topics related to cancer immunotherapy. Also included herein is a detailed explanation of the various concepts and applications of this branch of therapy. This book includes contributions of experts and scientists which will provide innovative insights into this field.