“Micro” means something invisible to the naked eye, whilst “biome” refers to a collection of organisms that live in a particular habitat. Therefore, the microbiome is defined as the collection of microbes (and their genes) within a community.
These microbes include:
- Bacteria
- Archaea
- Fungi
- Protists
- Viruses
Since these microbes are all over our body¹, we have different microbiomes, such as the skin, oral and gut microbiome – the latter of which is the most densely populated.