A microorganism, or microbe, [a] is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from …

Dec 4, 2025 · The major groups of microorganisms—namely bacteria, archaea, fungi (yeasts and molds), algae, protozoa, and viruses—are summarized below. Links to the more detailed articles on …

Aug 4, 2025 · Microorganisms—organisms too small to be seen with the naked eye—pervade every corner of the planet. They flourish in soil, water, air, and even the most extreme environments …

Microorganisms, also known as microbes, are tiny living organisms that are invisible to the naked eye. They include a diverse group of microscopic life forms such as bacteria, archaea, fungi, protists, and …

Microorganisms differ from each other not only in size, but also in structure, habitat, metabolism, and many other characteristics. While we typically think of microorganisms as being unicellular, there are …

Microorganisms constitute a vast and diverse group of life forms that span all domains. Bacteria and archaea are prokaryotes that lack a membrane-bound nucleus. They vary in morphology, …

Microorganisms are very diverse; they include bacteria, fungi, algae, and protozoa; microscopic plants (green algae); and animals such as rotifers and planarians. Some microbiologists also include …

Microbes, which are also called micro-organisms, are a group of organisms that are too small to be seen with the naked eye. Despite being even smaller than the human cell, microbes still vary dramatically …

Microorganisms can be found almost anywhere in the taxonomic organization of life on the planet. Bacteria and archaea are almost always microscopic, while a number of eukaryotes are also …

Dec 4, 2025 · Microbiology, the scientific study of microorganisms, a diverse group of generally minute simple life-forms, including bacteria, algae, and viruses. The field is concerned with the structure, …