Specific recognition of antigens refers to an event that occurs in the body’s immune system. When the body is infected with a disease, or when a vaccination is given, the immune system is exposed to antigens that stimulate the body to produce antibodies, which are called B cells, and in the process of producing antibodies and clearing these antigens, the B cells gain immunity to the antigen. These B cells then differentiate and mature into plasma cells that are stored when the body is exposed to similar antigens again, i.e., when it is infected with such pathogenic microorganisms again, or when it is infected with pathogenic microorganisms after having previously been infected with them and having acquired such immunity. At this time, these mature plasma cells with memory will recognize this antigen and quickly produce a large number of antibodies to neutralize or remove this pathogenic microorganism to stop the body from being infected.