Microbes are single-celled or multi-cellular organisms that are too small to be seen with the naked eye. They include bacteria, archaea, protozoa, and viruses. Microbes are found in all environments on Earth, from the hot springs of Yellowstone National Park to the deep ocean floor. In fact, it is estimated that there are more microbes on Earth than there are stars in the Milky Way galaxy!
The study of microbes is called microbiology. Scientists who study microbes are called microbiologists. Microbiology is a branch of science that includes many different subfields, such as immunology (the study of the immune system), virology (the study of viruses), and mycology (the study of fungi).
Microbes play an important role in our lives. Some cause diseases, while others help us digest food or make vitamins. Some microbes even help plants grow! We could not live without them!