Immunology is a division of biology that covers the study of immune systems in all organisms. Immunology records, measures, and contextualizes the physiological functioning of the immune system in conditions of both health and diseases; malfunctions of the immune system in immunological disorders like autoimmune diseases, hypersensitivities, immune deficiency, and transplant rejection and the physical, chemical, and physiological characteristics of the components of the immune system in vitro, in vivo and in situ.