Public health is the art of preventing many diseases, increasing the span of life and promoting health through the informed efforts and choices of the society, many organizations both private and public, communities and the individual human beings. It is based on concerns for overall threats to the society which is based on population and health analysis. The population can be handful of individuals or may be as large scale as many continents. The public health is subdivided into many categories such as epidemiology, biostatics and various health services. The main focus of this intervention is prevention of the disease rather than treating it through surveillance of cases. It is also about preventing the infectious diseases by the process of vaccination. Various other tasks are performed such as distribution of free condoms in public places hence spreading awareness about aids. The two approaches to health science are study and research, both being equally important. These help in understanding the nature of humans, their functioning and curing the diseases that might occur to them. The health research is based on various basic sciences such as biology, chemistry and physics as well as other multidisciplinary fields such as medical sociology. The other fields which have contributed significantly are biochemistry, epidemiology and genetics.