The Immunology (Bodys Resistance)
In the process of evolution, the body of human beings (including higher animals) have developed the property of distinguishing self and nonself; the self is accepted and nonself is rejected or degraded. For the rejection or degradation of nonself, organism’s body have evolved various mechanisms, which are collectively grouped under the name resistance (defence) or immunity.* The resistance (defence) or immunity is, therefore, the insusceptibility of the body to the effect of nonself factors like pathogenic microorganisms, their toxin or other kinds of foreign substances. The branch of biology that deals with resistance or immunity in humans (incl. animals) is called immunology.

Nonspecific Resistance
Nonspecific resistance (or nonspecific immunity) refers to defence devices that exist on or in the body and interact with pathogenic factors nonspecifically to make the body nonsusceptible to the effects of those factors.

Specific Resistance (or Acquired Immunity)
Specific resistance (or acquired immunity) is that which develops in the body after birth as a result of the formation of specific antibodies (or antibody like surface receptors) in response to specific antigen, or as a result of the introduction of antibodies produced by other organisms.