According to the Turkish Language Association Dictionary of Veterinary Medicine Terms, microorganisms are living organisms including bacteria, fungi, protozoa, and microscopic algae. Although there has been various information about some effects and usage areas of microorganisms for centuries, microorganisms were first seen and started to be studied in 1675 with Leewenhoek's discovery of the microscope. Within 200 years, Louis Pasteur proved some of the functions of microorganisms in the emergence of undesirable flavours in winemaking in his studies on the fermentation stage and concluded that heat treatment has an effect on the death of unwanted microorganisms. This practice, called pasteurization, is still accepted today. At that time, Robert Koch's studies also made essential contributions to microbiology, and his studies in this field have continued with rapid development until today. It contains basic information in terms of understanding the diversity and properties of microorganisms and bacteria.