Most bacteria have strong cell walls (Slide 0) which protect them from damage as well as other structures present (e.g. flagellum and pillus for locomotion (Slides 0-0) make them to survive in many diverse habitats ranging from hot springs to glaciers in Antarctica.

Though some bacteria are disease-producing agents (pathogenic) that attack human beings, other animals and/or plants, most are beneficial. Many act as decomposers, destroying the dead bodies and bodily wastes of other organisms and in the process, recycling important compounds from these organisms to environmental reservoirs where they become available to other living things. Some bacteria are used in industrial and manufacturing processes such as yoghurt and cheese making bacteria. Finally, study of bacteria enabled biologists to learn many important principles about life that have proved applicable to other organisms including ourselves.