Medicine (UK English /ˈmɛdsɨn/, /ˈmɛdɨsɨn/; US English /ˈmɛdɨsɨn/) is the science or practice of the diagnosis, treatment, and prevention of disease. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness.Medicine has existed for thousands of years, during most of which it was an art (an area of skill and knowledge) that frequently had connections to the religious and philosophical beliefs of each culture. For example, a medicine man would apply herbs and say prayers for healing, or an ancient philosopher and physician would apply bloodletting according to the theories of humorism. In recent centuries, since the advent of science, most medicine has become a combination of art and science (both basic and applied, under the umbrella of medical science). Thus, while the perfect stitching technique for suturing an artery is still an art that surgeons learn by practicing, the knowledge of what happens at the cellular and molecular level in the tissues being stitched comes from science. The older, prescientific forms of medicine are now known as traditional medicine and folk medicine. Although they are no longer the sole type of medicine, they are still used to complement scientific medicine and are thus called complementary and alternative medicine (CAM). For example, although acupuncture and herbal medicine are ancient arts that include unscientific components, they can still sometimes provide relief of pain, symptoms, or anxiety and are thus still valued by many patients regardless of the chemical or physical mechanisms by which they work. Thus they continue to have value in health care, within the limits of safety and efficacy. (In contrast, medicine outside the bounds of safety and efficacy is called quackery.) Contemporary medicine applies biomedical sciences, biomedical research, genetics and medical technology to diagnose, treat, and prevent injury and disease, typically through medication or surgery, but also through therapies as diverse as psychotherapy, external splints and traction, prostheses, biologics, pharmaceuticals, ionizing radiation among others.The word medicine is derived from the Latin ars medicina, meaning the art of healing.