How does a vaccine for a particular disease immunise the human body against that disease?

A vaccine for a particular disease immunises the human body against that disease based on the property of 'memory' of the immune system. During vaccination, antigenic proteins of a particular pathogen of a disease is introduced into the body. The antibodies are produced in the body against these antigens that would neutralise the pathogenic agents during their infection. Thus, the vaccines generate memory – B and T-cells that recognise the pathogen quickly on subsequent exposure and fight against the antigens with a production of antibodies.