» Immunization, or immunisation,'s the process by which an individual's immune system becomes fortified against an agent (known as the immunogen). When an immune system's exposed to molecules that're foreign to the body (non-self), it'll orchestrate an immune response, but it can also develop the ability to quickly respond to a subsequent encounter (through immunological memory). This's a function of the adaptive immune system. Therefore, by exposing an animal to an immunogen in a controlled w… (More on Immunisation)