Microbiology is the study of microscopic organisms, either unicellular (single cell), multicellular ( cell colony), or a cellular (lacking cells).

Microbiology includes the disciplines virology, mycology, parasitology, bacteriology, and so on. Microbiologists traditionally relied on culture, staining, and microscopy. Apparently, Microbiologists often rely on extraction or detection of nucleic acid, either DNA or RNA sequences.

Viruses are not always classified as organisms, as they have been identified either as very simple microorganisms or very complex molecules. Prions, never considered microorganisms, have been investigated by virologists, however, as the clinical effects traced to them were originally presumed due to chronic viral infections, and virologists took search—discovering "infectious proteins".