The WHO defines health as a state of complete physical, mental, and social well-being, not merely the absence of disease or infirmity.

Illness is often defined in relation to health, disease, and sickness, although these terms can have different meanings in different contexts.

The biomedical model of illness emphasizes the role of biological factors, such as pathogens and genetic predispositions, in the development of disease.

The biopsychosocial model of illness acknowledges the contributions of biological, psychological, and social factors in the development and experience of illness.

Salutogenesis emphasizes the study of factors that promote health and well-being, rather than solely focusing on the causes of disease.

Illness behavior encompasses the actions that individuals take to cope with and manage their illness, such as seeking medical care, adhering to treatment plans, and making lifestyle changes.

The sick role describes the expectations and behaviors that society assigns to individuals who are ill, including the exemption from certain responsibilities and the obligation to seek medical care.

The social construction of illness emphasizes the role of social and cultural factors in shaping the definition, perception, and experience of illness.

Medicalization involves the transformation of a condition or behavior into a medical problem, often through the involvement of medical professionals and institutions.

Demedicalization involves the process by which a condition or behavior is no longer defined as a medical problem, often due to changes in social, cultural, or scientific understandings.

Health inequality encompasses differences in health status, access to healthcare, and health outcomes between different population groups, often due to social, economic, and political factors.

Health promotion involves actions taken to enhance overall health and well-being, including promoting healthy behaviors, creating supportive environments, and addressing social determinants of health.

Disease prevention involves actions taken to reduce the risk of developing a disease, such as immunization, screening, and lifestyle modifications.

Health care encompasses services provided to diagnose, treat, manage, promote, and prevent illness and disease, as well as to promote overall health and well-being.

Health policy involves decisions and actions taken by governments and organizations to promote health, prevent disease, and improve healthcare systems.