The book contains advanced information about different immune response generated, by the body. It narrates a general concept about different immunological aspects, explaining about the response generated by the body against different viral infection. We have tried to cover the autoimmune diseases, immune response generated by the body in cancer and other immunodeficiency diseases and the immune response generated by body during Corona disease. We have made a serious attempt to simplify the complicated language of immunology into a simple and understandable version.