Alternative medicine is any form of practice that is outside the realm of conventional modern medicine. It covers a broad range of healing philosophies, approaches, and therapies. Most of these treatments and health care practices are not taught widely in medical schools. Examples are naturopathy, chiropractic, ayurveda, homeopathy and acupuncture. (A complete listing of alternative medical practices are given later.)

If alternative medicine or therapy is used alone or instead of conventional medicine, it is called "alternative" medicine. If the treatment or therapy is done along with or in addition to conventional medicine, it is referred to as "Complementary Medicine" as the two practices complements each other. For example, many Chinese hospitals use acupuncture to reduce the pain during the surgery instead of anesthetics. This is complementary medicine. Later, we refer to the use of sesame oil as a complementary treatment for cancer. Dean Ornish uses life style changes to combat heart disease. These are all examples of complementary medicine.

Many of the alternative practices pay attention to the mental, emotional, and spiritual aspects of health, in addition to the physical body. Therapies like hypnosis and visualization claims to be able to change physical conditions through purely mental interventions. They believe that our bodies are remarkably resilient machines, capable, with some occasional prodding or intervention, of healing themselves. The name "holistic medicine" came from this unification of the mind and the body. Holistic practitioners treat the "whole person" as opposed to the individual organs of the body where symptoms occur. The importance of self care and preventing illness are stressed by holistic practitioners.

Any therapy that relies on the body's own healing powers may be considered natural medicine. These include herbal remedies, diet and water therapies.