Reiki is a study of how energy effects the body. People try to chanel their energy into you in order to envoke so sort of reaction within the targets body.

Reiki is a healing therapy based around the concept of Chakras. In order to practice Reiki a practitioner has to be "attuned" (basically another word for the initiation/training process, that helps them to centre their energy correctly and be able to share it with others). There three levels of practitioner Reiki 1, Reiki 2 and Reiki Master (who have the ability to attune others). The process basically consists of the patient lying or sitting whilst the practitioner places their hands onto the various chakras and visualises energy "flowing" into the other person. Unlike faith healing it isn't attached to a specific religion or set of spiritual beliefs, and doesn't (usually) claim to heal physical illness (although many complementary practitioners of more physical therapies are Reiki trained and use the principles of Reiki to help their treatments) and is considered most valuable to help with mild psychological difficulties such as stress, mild shock, depression etc. Many Reiki Masters do not advocate charging for the treatments. Whether it has any scientific basis I don't know, but the treatments I have have certainly been very relaxing.

You can find a good answer at... http://www.reiki-energy.org.uk/what_is_reiki.html I am attuned to level two reiki and I think it is fantastic and is capable of many things.

I have been a reiki practioner for about a year. Reiki is energy that flows from the universe through someone who has been attuned and out of their hands. They then put there hands on different places either on your body or a few inches above it while you are seated in a chair or on a massage table. The client can feel many different things heat, cold, tingling or absolutly nothing. It should not hurt. It is not known how it works. Reiki is NOT a replacement for medical care it works with standard care. Untill you get used to them you may feel tired after a treatment or you may feel energized. Everybody's body responds differently. Also it is suggested to drink lots of fluids afterward.