This refers to the targeted induction of immunity to a specific antigen by bringing the body's immune system into contact with this antigen (e.g. an attenuated pathogen), thereby triggering an immune response. Immunity can also result from the disease itself; this process is also called immunization.
In active immun ization, the body is induced to produce specific antibodies through contact with an immunogen without itself being harmed. In passive immunization , antibodies are supplied to the organism.