Reiki is a Japanese technique for stress reduction and relaxation that also promotes healing. It is administered by "laying on hands" and is based on the idea that an unseen "life force energy" flows through us and is what causes us to be alive. If one's "life force energy" is low, then we are more likely to get sick or feel stress, and if it is high, we are more capable of being happy and healthy.

The word Reiki is made of two Japanese words - Rei which means "God's Wisdom or the Higher Power" and Ki which is "life force energy". So Reiki is actually "spiritually guided life force energy."
A treatment feels like a wonderful glowing radiance that flows through and around you. Reiki treats the whole person including body, emotions, mind and spirit creating many beneficial effects that include relaxation and feelings of peace, security and wellbeing. Many have reported miraculous results.

Reiki is a simple, natural and safe method of spiritual healing and self-improvement that everyone can use. It has been effective in helping virtually every known illness and malady and always creates a beneficial effect. It also works in conjunction with all other medical or therapeutic techniques to relieve side effects and promote recovery. http://www.reiki.org/faq/WhatIsReiki.html

Additionally, in my practice, Reiki is used in hospitals. It is especially effective pre and post surgery; with oncology patients as a way to help ease effects of chemotherapy/radiation and gentle and comforting for end of life care sessions. My trainings are with Lavender Touch Reiki for 1 & 2, and Malia Okin for Reiki Mastery and Angelic Attunements.