Immunology is a branch that deals with barrier surfaces. It's the first line of defence against infections, and it's overlapping. It is a one-of-a-kind immunologic mechanism that protects humans against infection. There are numerous types of Immunology barriers (blood brain barrier, blood cerebro-spinal fluid barrier, and fluid barrier), as well as mechanical and biological barriers that protect organs from infection. Major physical and immunological barriers to infection are the lungs, intestines, and skin. A number of air and food borne infections, allergies, and other environmental contaminants enter the body through these organs. They have a one-of-a-kind ability to sustain homeostasis despite frequent external stimuli. When this property is impaired, a variety of diseases develop. Despite the fact that the underlying processes of some of these diseases are unknown, it is now obvious that immunological imbalances play a role in many of them.