Microbiology is the study of the large and diverse group of living organisms of microscopic size which includes viruses, bacteria, fungi, algae, worms and protozoa. Microbiology is the science which is concerned with the study of micro-organisms including their distribution and role in the environment and their relationship to other living organisms including humans (in health and disease) and other animals. An understanding of the basic nature and molecular structure of the microbes has been a major factor in the advancement of molecular biology as a scientific discipline and in establishing microbial genetics as an advancing science.

Microbiology plays a central role as one of the basic biological sciences and has been at the forefront of research aimed at probing the nature of life processes. During the past several decades many of the major discoveries which have helped to elucidate the fundamental principles of molecular biology, biochemistry and genetics have arisen from studies using micro-organisms. Micro-organisms are also closely associated with the health and welfare of animals including human beings, with some micro-organisms having beneficial effects and others having detrimental effects.

Many large-scale industrial processes, involved in the manufacture of food and beverages, as well as the production of many pharmaceutical, chemical and agricultural products, are microbiologically based. Microbiology also plays a vital part in the control of pollution in the environment through treatment processes for water and industrial, agricultural and domestic wastes.