Reiki is a form of energy healing that originated in Japan in the early 20th century. It is based on the belief that a practitioner can channel universal energy to help balance the energy centres in the body, promoting relaxation and healing. 

The practice of Reiki was developed by Mikao Usui, a Japanese spiritual teacher, who is credited with rediscovering the ancient healing technique. 

Reiki is often used as a complementary therapy to traditional medical treatments, and many people find it helpful in reducing stress and promoting overall well-being.