The World Health Organization (WHO) described it in 1948 as: “A state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.” In 1984, a WHO health promotion initiative led to expansion of the original WHO description, which can be abbreviated to: “The extent to which an individual or a group is able to realize aspirations and satisfy needs, and to change or cope with the environment. Health is a resource for everyday life, not the objective of living; it is a positive concept, emphasizing social and personal resources as well as physical capabilities."

Source: Porta M. A Dictionary of Epidemiology. 5th ed. New York, NY: Oxford University Press; 2008. 

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