In biology,<unk> is the capability of multicellular organisms to resist harmful microorganisms.<unk> involves both specific and nonspecific components. The nonspecific components act as barriers or eliminators of a wide range of pathogens irrespective of their antigenic make-up. Other components of the immune system adapt themselves to each new disease encountered and can generate pathogen-specific<unk> <unk> is a complex biological system that can recognize and tolerate whatever belongs to the self, and to recognize and reject what is foreign (non-self).
Immunity 
Social immunity
Histocompatibility
Immunocompetence
Immune response
Humoral immunity
Tissue tropism
Antigenicity