Question

What do you mean by immunization?

Answer 1

Immunization is defined as the process in which a vaccine is administered and is given in a person's body and the person is made immune or resistant to an infectious disease. Vaccines increase and strengthen the body's immune system to protect the person against subsequent infection or disease.

Complete answer:
According to WHO, Immunization is defined as the process through which a person is made immune or resistant to an infectious disease, typically by the administration of a vaccine. Vaccines increase responsiveness of the body's own immune system to protect the person against subsequent infection or disease. To develop an immune response, live, attenuated organisms which leads to the disease are inserted into the person's body.
A small dose of administered virus or bacteria replicates in the body and give rise to enough organisms that our immune system activates against that virus or bacteria to kill it. As the inserted that virus or bacteria to kill it.
As the inserted organism is attenuated, it cannot lead to any kind of disease in that person. When our immune system activates, it produces antibodies against that bacteria or virus and kills them. Now, antibodies against that particular organism are from the start present in the body.

When that organism will actually attack, antibodies which are already existing in the body will kill that organism and disease will not occur. This is the principle of immunization which is given and provided by Edward Jenner.

Note: We should also have knowledge about active and passive immunization. In passive immunization, direct antibodies are provided into the person's body and in active immunization live, attenuated organism is provided and the person's body itself forms the antibodies.