Naturally acquired immunity develops when the organisms naturally contact with the infectious pathogen. As a result, the immune system produces antibodies against the pathogen antigens and develops immune memory to the specific antigens. Artificially acquired immunity develops when the specific antigens are introduced artificially. For instance, vaccination is performed to form artificially acquired immunity. Although the mechanism of the immunity formation is the same in both cases, they are different in the introduction of the antigens: naturally acquired immunity is related to the natural infection of the organism with the pathogen while artificially acquired immunity develops after vaccination - the artificial introduction of the pathogen or its isolated antigens.