The focus of public health interventions is to prevent and manage diseases, injuries and other health conditions through surveillance of cases and the promotion of healthy behavior, communities, and (in aspects relevant to human health) environments. Its aim is to prevent health problems from happening or re-occurring by implementing educational programs, developing policies, administering services and conducting research.[52] In many cases, treating a disease or controlling a pathogen can be vital to preventing it in others, such as during an outbreak. Vaccination programs and distribution of condoms to prevent the spread of communicable diseases are examples of common preventive public health measures, as are educational campaigns to promote vaccination and the use of condoms (including overcoming resistance to such).
When a clearer distinction is intended, healthy is used to describe the state of the object, and healthful describes its ability to impart health to the recipient. Vegetables in good condition are both healthy (i.e., not rotten or diseased) and healthful (i.e., they improve the eaters' health, compared to eating junk food). By contrast, a poisonous plant can be healthy, but it is not healthful to eat it.

The maintenance and promotion of health is achieved through different combination of physical, mental, and social well-being, together sometimes referred to as the "health triangle."[25][26] The WHO's 1986 Ottawa Charter for Health Promotion further stated that health is not just a state, but also "a resource for everyday life, not the objective of living. Health is a positive concept emphasizing social and personal resources, as well as physical capacities."[27]

healthy, sound, wholesome, robust, hale, well mean enjoying or indicative of good health. healthy implies full strength and vigor as well as freedom from signs of disease. a healthy family sound emphasizes the absence of disease, weakness, or malfunction. a sound heart wholesome implies appearance and behavior indicating soundness and balance. a face with a wholesome glow robust implies the opposite of all that is delicate or sickly. a lively, robust little boy hale applies particularly to robustness in old age. still hale at the age of eighty well implies merely freedom from disease or illness. she has never been a well person

The meaning of health has evolved over time. In keeping with the biomedical perspective, early definitions of health focused on the theme of the body's ability to function; health was seen as a state of normal function that could be disrupted from time to time by disease. An example of such a definition of health is: "a state characterized by anatomic, physiologic, and psychological integrity; ability to perform personally valued family, work, and community roles; ability to deal with physical, biological, psychological, and social stress".[7] Then in 1948, in a radical departure from previous definitions, the World Health Organization (WHO) proposed a definition that aimed higher: linking health to well-being, in terms of "physical, mental, and social well-being, and not merely the absence of disease and infirmity".[8] Although this definition was welcomed by some as being innovative, it was also criticized as being vague, excessively broad and was not construed as measurable. For a long time, it was set aside as an impractical ideal and most discussions of health returned to the practicality of the biomedical model.[9]