Final answer:
Normal flora that is virtually always present is referred to as resident microbiota, which are stable inhabitants contributing to the human microbiome and are distinct from transient microbiota that do not permanently reside in the body.
Step-by-step explanation:
Normal flora, which are virtually always present in or on our bodies, are referred to as resident microbiota. The term resident indicates these microorganisms consistently inhabit our bodies, forming the human microbiome along with transient microbiota. Unlike transient microbiota which are temporarily found and may include pathogenic organisms, resident microbiota form a staple part of our normal flora, contributing to health and well-being by aiding in various physiological processes. Changes in hygiene and diet can affect both resident and transient microbiota. An example of the importance of these microorganisms is seen when antibiotics eliminate many of the normal gut bacteria, allowing antibiotic-resistant species like Clostridium difficile to cause severe gastric issues.