Public health evolved through trial and error and with expanding scientific medical knowledge, at times controversial, often stimulated by war and natural disasters. The need for organized health protection grew as part of the development of community life, and in particular, urbanization and social reforms.Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals. Analyzing the determinants of health of a population and the threats it faces is the basis for public health.The public can be as small as a handful of people or as large as a village or an entire city in the case of a pandemic it may encompass several continents. The concept of health takes into account physical, psychological, and social well-being. There is a significant disparity in access to health care and public health initiatives between developed countries and developing countries, as well as within developing countries. In developing countries, public health infrastructures are still forming. There may not be enough trained healthcare workers, monetary resources, or, in some cases, sufficient knowledge to provide even a basic level of medical care and disease prevention. A major public health concern in developing countries is poor maternal and child health, exacerbated by malnutrition and poverty coupled with governments' reluctance in implementing public health policies.