"The human gut is home to trillions of microorganisms, which are collectively known as the microbiome. These microbes play a vital part in our gut health, supporting digestion and the synthesis of vitamins.
At this moment, two to six pounds of microbes are living in and on you. This ecosystem of trillions of microbes is also known as your microbiome, which contains bacteria and other microorganisms that are both beneficial and detrimental to your health."
"Certain microbiota perform tasks that are known to be useful to the human host; the role of most resident microorganisms is not well understood. Those that are expected to be present, and that under normal circumstances do not cause disease, are sometimes deemed normal flora or normal microbiota."