Public health is anxious with pressure to the overall health of a community based on population health analysis. Health is distinct and promoted differently by many organizations. The World Health Organization, the United Nations body that sets standards and provides global inspection of disease, defines health as: "A state of complete physical, mental and social well-being and not entirely the absence of disease or illness." Public health experts concur this definition is incomplete. Other components included in an individual's health are dietary, religious, and intellectual.

The population in inquiry can be as big as a handful of public or, in the case of a pandemic, whole continent. Public health has many sub-fields, but is typically divided into the category of epidemiology, biostatistics and health military. Ecological, social and behavioral health, and occupational health, is also main fields in public health. Another definition by Derek Wanless in the UK in February 2004 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 persons."

In some ways, public health is a modern concept, although it has roots in antique. From the early beginnings of human development, it was familiar that polluted water and lack of proper waste disposal may spread vector-borne diseases. Early religions attempted to standardize behavior that specifically related to health, from types of food eaten, to the scope which certain behaviors could be indulged, such as drinking alcohol or sexual relations. The establishment of governments placed responsibility on leaders to develop public health policies and programs to gain some understanding of the causes of disease to ensure strength, success, and retain order.

One of the most important public health issues facing the world at present is HIV/AIDS. Tuberculosis, which claimed the lives of authors Franz Kafka and Charlotte Bronte, and composer Franz Schubert, among others, is also reemerging as a major worry due to the rise of HIV/AIDS-related infections and the development of strains contest to normal antibiotics. Another major public health apprehension is diabetes. In 2006, according to the World Health Organization, at least 171 million people global suffer from diabetes. Its occurrence is increasing rapidly, and it is estimated that by the year 2030, this number will twice.