**Abstract**

The quality of life concept was born in the 1970s within the social sciences and soon it arrived in the field of medicine and health, where this notion has been considered as a criterion to evaluate health interventions. The World Health Organization defines quality of life as the subjective perception individuals have of their life position, in their cultural context and value system, in relation to their objectives, expectations, standards, and worries. It is a very complex and articulated conception, and as a matter of fact in this chapter, we will analyze an overview about this topic, to examine it in depth, and clarify this concept; synthetically, we can note that the quality of life is specified by the perception of one's physical, psychological, and emotional health, by the degree of personal independence, by social relations, and by the type of interaction with one's context. We can note that this construct is broader than that of health, it is not a synonym of it, and it is also important to point out that the definition of the World Health Organization about this topic connects elements resulting from an enormous amount of studies. In this sense, being healthy is considered one of the numerous quality of life dimensions, and health-facilitating behaviors are judged as predictors of the quality of life itself. Moreover, the definition of quality of life always includes a reference to the individual's physical state, but it is not considered only on the basis of a person's bodily functions, detectable with standardized parameters, since it is described in relation to the perceived satisfaction degree regarding this functionality level. This kind of definition shifts the emphasis from the objectively definable functionality to the subjectivity dimension; the detection of both these two aspects can constitute a reliable quality of life measure. Furthermore, we can note that the most common method for measuring quality of life is the administration of questionnaires and, in addition, that there are two questionnaire types: generic and specific for pathology. Finally, this chapter highlights the importance of the biopsychosocial paradigm in relation to the quality of life concept.

**Keywords:** quality of life, definition, World Health Organization, subjective dimensions, psychosocial factors, biopsychosocial paradigm, questionnaires
