Microbiology is the study of very small, usually single-celled organisms known as microbes. Even though you can’t see them without a microscope, microbes are everywhere you go. Examples include bacteria, fungi, microscopic plants and animals such as plankton.
These red bacteria cause Salmonella NIAID
The first microbes appeared on earth about 3.5 billion years ago. They are very important in sustaining life on our planet, and can be found in even the most hostile of environments such as hot deserts and the deep sea. Amazingly, microbes represent around 60 percent of the biomass of all life on Earth! In fact, your body contains over twice as many microbe cells than your own body cells!