Microbiology encompasses the study of:

* Bacteria: single-celled prokaryotes

* Archaea: another type of single-celled prokaryote

* Fungi: eukaryotic organisms, including molds, yeasts, and mushrooms

* Protozoa: single-celled eukaryotic organisms

* Viruses: non-living entities that require a host to replicate

* Algae: photosynthetic eukaryotic organisms

Microbiologists study the characteristics, growth, metabolism, genetics, and interactions of these organisms. They also explore the roles they play in the environment, human health, and industry.