The ability of the body to fight against the pathogen is called immunity.
The immunity which is developed after the direct exposure to the pathogen or antigen is called active immunity. In this immunity, a person's own cells produce antibodies in response to infection.
The immunity gained by an organism through vaccines or antidotes is known as passive immunity. In this type of immunity, there will be no exposure to the pathogen directly. Ready-made antibodies are directly injected into a person to protect the body against foreign agents such as the snake poison. Thus, injection of an antidote of a snake is an example of passive immunity.
When the immune system recognizes the body cells as a foreign substance and attacks one's own healthy body cells, such immunity is known as autoimmunity. The immunity that is present since the time of birth is called innate immunity. This type of immunity is inherited from the parents and protects the individual throughout his life.