Public Health: the science and art of preventing disease, prolonging life and promoting human health through organized efforts and informed choices of society, organizations, public and private, communities and individuals." Analyzing the health of a population and the threats is the basis for public health. The "public" in question can be as small as a handful of people, an entire village or it can be as large as several continents, in the case of a pandemic. "Health" takes into account physical, mental and social well-being. It is not merely the absence of disease or infirmity, according to the World Health Organization.