Health, as defined by the World Health Organization, is a state of full physical, emotional and social well being and not just the absence of sickness and disease. A wide variety of other definitions have also been used over the years for many different purposes. In medicine, health is described as having a capacity to resist infection, cope with injury, live well, and attain physical well-being. In other words, health is equivalent to the ability to sustain life.

Although there are numerous definitions for health, they all agree on one thing: absence of diseases or illnesses and proper protection against disease. This protection is achieved through a healthy lifestyle that includes a healthy diet, regular exercise, and limitation of exposure to hazardous substances. People who have a healthy lifestyle are less likely to develop chronic conditions such as cancer, heart disease, and respiratory disease. They also have a higher quality of life than those who suffer from ill-health or diseases caused by unhealthy lifestyles.

The concept of wellness and ill-health is interrelated, but it should be understood that they are often separate entities. Wellness refers to managing the risk factors associated with illness or disease while illness focuses on treating the symptoms of the disease. Thus, wellness can be achieved by improving one’s lifestyle, while illness can be prevented by avoiding exposure to risk factors.