医学是以诊断、治疗和预防生理和心理疾病和提高人体自身素质为目的的应用科学。狭义的医学只是疾病的治疗，但也有说法称预防医学为第一医学，临床医学为第二医学，复健医学为第三医学。医学的科学面是应用基础医学的理论与发现，例如生化、生理、微生物学、解剖、病理学、药理学、统计学、流行病学等，来治疗疾病与促进健康。然而，医学也具有人文与艺术的一面，它关注的不仅是人体的器官和疾病，而是人的健康和生命。「生理、心理、社会模式」是广为接受的理论，而其他如「生理心理灵性社会的照顾」、「全人、全队、全程、全家的医疗」也都是现代医学的重要理论。随着医学模式的转变，医学的人文性受到越来越多的重视。医学伦理目前最广为人知的是四初确原则方法论：「自主、行善、不伤害、正义」。

Medicine (British English /ˈmɛdsᵻn/; American English /ˈmɛdᵻsᵻn/) is the science and practice of the diagnosis, treatment, and prevention of disease. The word medicine is derived from Latin medicus, meaning "a physician". Medicine encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness. Contemporary medicine applies biomedical sciences, biomedical research, genetics, and medical technology to diagnose, treat, and prevent injury and disease, typically through pharmaceuticals or surgery, but also through therapies as diverse as psychotherapy, external splints and traction, medical devices, biologics, and ionizing radiation, amongst others.