Reiki originates from Japan in the 1920's it was developed as a path of self-development and spiritual enlightenment. Reiki is about finding oneness with yourself and having balance within your life. It has developed into a healing energy, which most practitioners use to treat themselves and others. Reiki isn't linked to any religion and it's founder Mikao Usui developed a set of rules to live by, reiki students and practitioners endeavor to live by these rules on a daily basis.
Reiki channels energy through the practitioner from the surrounding atmosphere (chi) in to the patient or into the practitioner him/herself. When performing a treatment or a self-treatment the practitioner connects to the energy, asks for the energy to be used for the best intentions of the recipient and then places the hands (or hovers over the patient as Niki does) on the body, by using intuition the hands are then guided through a treatment which usually takes between 45mins to an hour. A practitioner will normally have a consultation with the person seeking reiki to ensure that they understand the process and to ensure that the medical profession has diagnosed serious conditions. In the treatment of animals, a vet should also have seen the animal first, reiki is a complementary therapy and not a diagnosis system.