Refers to a person's state of physical, mental and social well-being; usually it refers specifically to the state of being in good health, a state of complete physical, mental and social well-being, and does not consist only of the absence of disease or infirmity. In any organism health constitutes a form of homeostasis with inputs and outputs of energy and mass in approximate equilibrium allowing for growth and continued survival. In humans, a subjective feeling of well-being coming from somatic and cognitive perceptions is considered an essential component of health.