Alternative medicine describes practices used in place of conventional medical treatments. Complementary medicine describes alternative medicine used in conjunction with conventional medicine. The term complementary and alternative medicine (CAM) is an umbrella term for both branches. Alternative medicine includes practices that incorporate spiritual, metaphysical, or religious underpinnings; non-European medical traditions, or newly developed approaches to healing. There are almost 500 such systems.
The National Center for Complementary and Alternative Medicine defines complementary and alternative medicine as "a group of diverse medical and health care systems, practices, and products that are not presently considered to be part of conventional medicine". It also defines integrative medicine as "mainstream medical therapies and CAM therapies for which there is some high-quality scientific evidence of safety and effectiveness". Ralph Snyderman and Andrew Weil state "integrative medicine is not synonymous with complementary and alternative medicine (CAM). It has a far larger meaning and mission in that it calls for restoration of the focus of medicine on health and healing and emphasizes the centrality of the patient-physician relationship".