What is the human microbiome? Trillions of bacteria, viruses, and other microbes live in our bodies. These microbes, which outnumber the cells in our bodies, work together to regulate processes critical to life including metabolism and the immune system. The genetic material of this microbial community is at least 100 times greater than the genetic material of the entire human body. It is the genetic material of this microbial community that forms the human microbiome. The scientific term for the collection of microbes themselves is microbiota. Because of its complexity, diverse microbial populations, and dense number of cells, the intestinal microbiota has been of special interest to physicians and medical researchers.