This document provides a history and overview of immunology. It discusses how immunology stems from concepts of protection from disease. The immune system involves both nonspecific innate immunity and specific adaptive immunity. Key developments included Jenner's smallpox vaccine in 1796, Pasteur's vaccines for rabies and other diseases in the late 1800s, the discoveries of phagocytic cells, antibodies, and T and B cells. Major figures who advanced the field included Jenner, Pasteur, von Behring, Ehrlich, Metchnikoff, Milstein, Köhler, Tonegawa, and Doherty and Zinkernagel. The document also outlines the cells of the immune system originating from bone