Spiritual healing - Reiki practitioners believe it is a universal life energy which enters the body through the 7th chakra after which it flows through the rest of the body. It is distributed from one person to another through the hands of a reiki practitioner by holding the hands on or above the part of the body that requires healing, or in case of an unspecified problem or the use of reiki as a relaxation practice a full treatment is given. This means every part of the body gets treated, please note that reiki energy when it is given travels through the entire body, although it is most concentrated on the spot where the hands are held.
Second degree reiki practitioners are capable of transmitting reiki energy over large distances to a specific person by means of three specific reiki symbols.
Third degree enables a practitioner to becom a Reiki Master. Fourth degree enables the Master to become Master-Teacer, thus capable of initiating others to Reiki.
What is commonly called Reiki is a spiritual practice founded by Mikao Usui. It is the universal vibrations of unconditonal love and harmony. It brings balance to mind, body and spirit and surrounds with harmony. It is simple yet profound. You can read more about what Reiki is here: http://naturalhealinglearning.com/what_is_reiki.html
Also, it is highly recommended to read Reiki facts on:
http://www.multihealing.com/Reiki%20courses/Reiki%20Facts.pdf