The microbiology is the science in charge of the study and analysis of microorganisms, living things small not visible to the human eye, also known as microbes. Microbes are those organisms that are only visible through the microscope: prokaryotic and simple eukaryotic organisms.
They can be made up of a single cell (unicellular), or of small cell aggregates formed by cells without cell differentiation.
However, traditional microbiology has dealt especially with the pathogenic microorganisms of bacteria, viruses, and fungi, leaving the other microorganisms for other branches of biology to study.
In this topic we will not deal with bacteria because we already studied them when we saw the prokaryote.