Immunology is the branch of medical science that maps and measures the functioning of physiological aspects of the immune system, as well as deals with the diagnosis and treatment of diseases related to it. It aims at finding cure for immune deficiency, autoimmune diseases, transplant rejection and hypersensitivities. It has applications in several disciplines such as parasitology, psychiatry, dermatology, virology, bacteriology, oncology and organ transplant. This book traces the progress of immunology and highlights some of its key concepts and applications. Different approaches, evaluations, methodologies and advanced studies on essential topics of this field have been included in it. Students, researchers, experts and all associated with the area of immunology will benefit alike from this book.