Microbiology is the study of organisms too small to be seen with the unaided eye

The development of microbiology as a discipline has depended on the availability of the microscope and the ability to isolate and grow pure cultures of microorganisms.

Many diseases are caused by viral, bacterial, fungal or protozoan infections.

Koch's postulates are used to establish a causal link between a microorganism and a disease

Microorganisms are not spontaneously generated from inanimate matter, but arise from other microorganisms.

Microorganisms have one of two fundamental cell types: procaryotic or eucaryotic.

Microorganisms are responsible for many of the changes observed in organic and inorganic matter, such as fermentation.