The study of bacteria is known as bacteriology, a branch of microbiology.A fundamental understanding of how a cell works has come through the study of microorganisms. But microbiology also is an applied science, helping agriculture, health and medicine and maintenance of the environment, as well as the biotechnology industry.Bacteria are classified into 5 groups according to their basic shapes: spherical (cocci), rod (bacilli), spiral (spirilla), comma (vibrios) or corkscrew (spirochaetes). They can exist as single cells, in pairs, chains or clusters. Artwork of bacterial cells becoming resistant to antibiotics.Bacteria are microscopic living organisms, usually one-celled, that can be found everywhere. They can be dangerous, such as when they cause infection, or beneficial, as in the process of fermentation (such as in wine) and that of decomposition.Bacteria are used in industry in a number of ways that generally exploit their natural metabolic capabilities. They are used in manufacture of foods and production of antibiotics, probiotics, drugs, vaccines, starter cultures, insecticides, enzymes, fuels and solvents.