Immunity is the resistance to the onset of disease after infection by harmful germs.
Immunity can be classified into two categories: innate and acquired immunity. Innate immunity
It is natural by birth (nonspecific or specific).
Nonspecific innate immunity is resistance to all infections in general.
Specific innate immunity is resistance to a particular kind of germ.
Passive acquired immunity
Immunity is provided from an outside source in the form of ready made antibodies.
It can be of two types naturally acquired and artificially acquired passive immunity.
Naturally acquired passive immunity is the readymade or the prepared mother's antibodies.
Artificially acquired passive immunity is the introduction of ready made antibodies having been produced in other animals.
Acquired immunity is a resistance to a disease which an individual acquires during his lifetime.
Acquired immunity can be actively acquired, which is produced in one's own body.
Passively acquired immunity can be either natural or artificial.
Types of immunity
There are two major types of immunity: innate or natural or nonspecific and acquired or adaptive immunity. 1. Innate immunity is inherited by the organism from the parents and protects it from birth throughout life. For example, humans have innate immunity against distemper, a fatal disease of dogs. 2. The immunity that an individual acquires after the birth is called acquired immunity or adaptive immunity. It is specific and mediated by antibodies or lymphocytes or both which make the antigen harmless.