The field of study that examines microorganisms is known as microbiology. Microorganisms are life forms that are too small to be seen with the eyes alone, and can include bacteria, protozoal parasites, viruses and fungi. Microscopes are used to be able to view and study these microorganisms, or microbes. The presence of microbes on Earth predates plant and animal life. Scientists estimate that they have been around for billions of years, and the estimated number of microbes in existence varies greatly. Some estimate as high as more than ten million species of microbes!
Some of the sub-disciplines included in microbiology are: Bacteriology (the study of bacteria), parasitology (the study of parasites), mycology (the study of fungi) and virology (the study of viruses). In our world, there are many uses of microbiology. There are many important uses of microbiology. In medicine, biologists are able to apply their knowledge of microbiology when researching the immune system and cures for various diseases. They also use that knowledge to understand how microbes form, grow and affect other cells. Environmentally, microbiologists use microorganisms to assess and repair damage. Microorganisms have also been used to degrade oil from an oil spill, decreasing the impact on the environment. Treatment of illness, including vaccine creation, uses microbiology in the field of biomedical research. In the food industry, keeping our food safe and extending shelf life of food are two examples of important uses of microbiology.
Sources:
http://www.newscientist.com/blog/shortsharpscience/2008/06/counting-in-bacterial-world.html
http://education.seattlepi.com/uses-microbiology-biology-6411.html
http://www.ls.manchester.ac.uk/schoolsandcommunity/resources/generalinfo/whatismicrobiology/
http://infectiousdiseases.about.com/od/glossary/g/Microbiology.htm