Quality of life (QoL) is a concept which aims to capture the well-being, whether of a population or individual, regarding both positive and negative elements within the entirety of their existence at a specific point in time. For example, common facets of QoL include personal health (physical, mental, and spiritual), relationships, education status, work environment, social status, wealth, a sense of security and safety, freedom, autonomy in decision-making, social-belonging and their physical surroundings.

The World Health Organization provides an explanation of QoL as a subjective evaluation of one's perception of their reality relative to their goals as observed through the lens of their culture and value system. The Quality of Life Research Unit at the University of Toronto defines QoL as how much a person can enjoy the valued possibilities of his or her life. It is essential to recognize the difference between QoL and other somewhat similar concepts which might get easily confused in the literature, such as the standard of living and health-related quality of life. QoL differs from the former in that standard of living is largely based on economic status and income.

QoL differs from the public health measure health-related quality of life, in that the latter is a measure which explores the connection between health and QoL. As there has been recognized difficulty with arriving at a universally accepted definition and measurement, recent studies have attempted to re-frame QoL into separate domains. One example of this re-framing is the "engaged theory," which takes QoL and divides it into four main domains: economics, culture, politics, and ecology.[1][2][3][4]

As alluded to in the previous section, the primary concern with the concept of QoL is a lack of a uniform definition. Compared to measures which are financial or can be otherwise measured quantitatively, such as gross domestic product, QoL remains elusive in an exact means of measurement across world cultures, regions, and demographics. There remains a push by many academic circles to break QoL into smaller components for more accurate and meaningful evaluation. One example is dividing the concept into domains (engaged theory), while other approach divides QoL into the ideas of personal well-being and life evaluation. This divide remains a widely debated topic in the literature.[5][2][6]

The concept of quality of life remains relevant to all clinical settings. It is of paramount importance in some fields of medicine, such as hospice and palliative care, where the aggressive pursuit of a cure is set aside with aims of instead satisfying patient goals and maximizing the patient's quality of life. It is important to clarify that studies show there is variability across individuals regarding how disease processes, symptoms, prognosis, and palliative treatments impact the quality of life. It is therefore worth emphasizing that assessing QoL through a limited definition or applying a particular model to all patients, would be an error as the literature stands. While there is no shortage of textbook definitions, perhaps the most accurate meaning of QoL is the definition the patient provides when sitting across from their clinician.[7][8][9][10]