Immunology is the analysis of the immune system and it is significant in the medical and biological sciences. The immune system shields us from infection through various lines of defence. If the system is not functioning as it should, then it will result in diseases, such as autoimmunity, allergy and cancer. The immune response is not only the response of the organism to antigen stimulation but also a biological process of recognizing and eliminating antigen substances. Most of the elements in the immune system are cellular in origin and not related to any specific organ, but they are embedded or circulated in various tissues located throughout the body. Immunology has applications in countless medical disciplines, especially in the fields of organ transplantation, oncology, rheumatology, virology, bacteriology, parasitology, and dermatology.