What is a microorganism?

A microorganism is defined as any organism that is microscopic or submicroscopic in size. This encompasses a wide range of life forms, including bacteria, viruses, fungi, and protozoa. Their small size means they cannot be seen with the naked eye, typically requiring the use of a microscope for observation.

This definition is inclusive of various categories, not limited to harmful organisms or those that infect specific hosts. While some microorganisms can cause diseases, others play essential roles in processes such as fermentation, nutrient cycling, and as part of the human microbiome, which is beneficial for health. Understanding this broad definition is crucial for anyone studying biology, health sciences, or related fields since it highlights the diversity and significance of these organisms.