Microorganisms are tiny living things that are all around us! “Micro” means tiny and “Organism” means a living thing. This means that these living things can’t be seen by the naked eye. The 5 main types of Microorganisms are viruses, bacteria, fungi, algae, and protozoa. Some of the microorganisms can be helpful like helping turn milk into cheese and some can be bad like viruses that infect cells. Microorganisms can come in all shapes, sizes, and “personalities”.