Abstract
Normal flora is a natural and permanent place for a number of human microorganisms (bacteria, fungi, viruses, etc.) that exist under normal conditions without harm to a healthy human body. This is useful for the human body. These microorganisms are called normal flora, and in another term, they are referred to as commensal organisms that feed together with the host. Under normal conditions, the internal organs and systems of the body, such as the pancreas, spleen, liver, bladder, gall bladder, nervous system, and circulatory system, are sterile, but they can also become infected. In addition, a child who enters the world in a sterile form will soon acquire a normal flora through milk, food, and the environment. Normal flora is not the same in all humans but varies from person to person based on differences in their physiological, dietary, age, and geological conditions. First off, harmful bacteria cannot compete with the host for nutrients and intake sites in the terminal portion of the intestinal thanks to the existence of benign bacteria in a healthy person's body. Second, it is resistant to the antibacterial chemicals made by the bacteria in the last section of the intestines. Third, babies' immune systems expand and mature as a result of the buildup of microorganisms in their bodies. The fourth is that gut bacteria create certain crucial dietary components, such vitamin K, which aids in food absorption and digestion. (Although people obtain the required quantity of vitamin K from diet, in the event that there is a shortage of foods high in the vitamin, bacteria generate the vitamin to fulfill the body's requirements. Keywords: Normal Flora, disease, Immunity, Human body and Pathogen.