Attunement is the practice of opening thought and feeling to the source of wisdom and love which is within all people, increasing the flow of life-giving energy through the body, into the world.
Attunement is an energy medicine practice and a consciousness practice. So it is both the shared generation of life energy between two people, promoting health and wellbeing, and also a daily practice of spiritual centering and flow.
Attunement opens the gateways of consciousness and energy associated with the endocrine glands. In offering an Attunement, Practitioners emanate life current through one hand that connects with a gland, organ or another part of the human anatomy, and with the other hand connects to a corresponding point in the nervous system. Most often, Attunement is practiced without physical touch.
The practice of Attunement was developed by Lloyd Arthur Meeker in 1929, who wrote under the penname, Uranda. Meeker practiced and taught Attunement as a part of his spiritual teaching within the global network that arose out of his teaching, Emissaries of Divine Light. He and his associates developed the practice of Attunement through the 1940s and early 50s, and through Emissaries of Divine Light around the world, the practice continued to grow and flourish after his passing in 1954.
This Wikipedia article describes Attunement practice and history.