Reiki is a form of hands-on healing which was brought back into common practice in the 20th century by a man called Mikao Usui. It is an ancient art, and there are theories that it is linked to the healing miracles you read about in religious texts such as the bible.
Many believe that hands-on healing used to be commonplace before traditional medicine took over, and indeed many more isolated communities still have a healer. Anyone can learn hands-on healing, and some people are born with the ability.
This ancient art was forgotten about or kept hidden for many years but there are now many forms of healing that don’t involve traditional medicine, and reiki falls under the heading of holistic healing. In ‘olden days’ a healer may well have been classed as a witch, and that may be one of the reasons the ancient art died out.