Simple Definition:

The microbiome refers to all the microorganisms (such as bacteria, fungi, and viruses) that live in and on the body of a living organism (including humans, animals, and plants). These microorganisms play important roles in maintaining the health and functioning of their host, and they interact with each other and with the host’s cells.

For example, the bacteria in our gut microbiome help us digest food and produce certain vitamins that our bodies cannot make on their own.

Very Simple Definition:

The microbiome is all the tiny living things that live on and inside our bodies. They help us stay healthy by doing important jobs, like helping us digest food.