The human microbiome, which is comprised of all the microorganisms (the microbiota) that live on and in humans, plays an essential role in determining good health. Microbes cover every surface of our bodies, inside and out. They’re on our skin, inside our noses, mouths, whole respiratory tract, plentiful in our digestive tract, reproductive system, and so on. These microscopic life forms consist of thousands of species and outnumber our own 50 trillion cells by about 10 to one.