I'm close to getting an attunement for the master level and thought I'd share what Reiki means.
(Information taken from notes or teaching material)

Just for today
I will not anger
I will not worry
I will do my work honestly
I  will be kind to all people and
I will be appreciative of my many blessings
 

Reiki (pronounced Ray-Key) is a natural system of energy healing this modality involves the

transfer of energy from practitioner to patient to enhance the body's natural ability to

heal itself through the balancing of energy. It is the same energy, which brings forth all

life in the universe and nourishes it. This system of energy healing originated in India,

its over 3,000 years old. In the late 19th century Dr. Mikao Usui rediscovered the key which

led to the recovery of a thousand-year-old tradition of healing.

Rei  means universal, Reiki is more accurately interpreted to mean supernatural knowledge or

spiritual consciousness.

Ki  The Life Force It is also called the vital life force or the universal life force.

Throughout  various cultures across the world and time, it referred  by many names as  Chi,

Ki, Prana, fohat, Orgone, Odic force, Bioenergetic plasma, Divine breath, Cosmic Pulse,

Vital Fire and Vital force etc…

Life force plays an important role in everything we do. This is the nonphysical energy that

animates all living things. As long as something is alive, it has life force circulating

through it and surrounding it; when it dies, the life force departs. If your life force is

low, or if there is a restriction in its flow, you will be more vulnerable to illness. Very

often we tend to short-circuit our own energy system as a result of some traumatic event,

which has led to a shutdown or blockage in our physical, emotional, psychological or

spiritual bands of energy. When it is high, and flowing freely, you are less likely to get

sick. Energy healing is thus a process of promoting balance and harmony on all levels. This

Ki is present all around us and can be accumulated and guided by the intension.

A treatment feels like a wonderful glowing radiance that flows through you. Reiki treatment

impacts the physical, mental, emotional, and spiritual dimensions of human existence. Reiki

can relieve pain and enhance healing of all diseases and illnesses.

One transcends the physical limitations, and true healing occurs and with true healing some

amazing cures are produced as byproducts. Reiki is a simple, natural, and safe method of

spiritual healing and self-improvement that everyone can use.

It is done by placing the hands on or near the recipient. The practitioner runs Reiki Energy

while placing their hands on or over a series of locations on the recipients body.  Advanced

practitioners can also work remotely i.e. without physical contact.

Is Reiki a Religion?

While Reiki is spiritual in nature, it is not a religion. It has no dogma, and there is

nothing you must believe in order to learn and use Reiki. In fact, Reiki is not dependent on

belief at all and will work whether you believe in it or not. Because Reiki comes from

Divine Source. Reiki transcends all religious beliefs and is available to everyone who

learns to focus the mind on their true purpose of incarnation.
 

 What is Reiki, then?
Reiki is a spiritual healing technique and an energy healing technique; Spiritual healing

connects one with Universal Consciousness bring Spiritual growth by healing core

patterns/issues and helping one to remember the fullness of Who They Are. Energy healing

bring relief of pain and symptoms in the mind, body and emotions.
  

How Reiki Works?  

Reiki is so gentle, but powerful and effective also. It addresses not only the symptom but

also the cause of disease. Reiki treatment enhances the body's natural ability to heal

itself. Reiki treatment releases blocked energy and bring relief of pain and symptoms in the

mind, body and emotions. This life-force energy is not inert or lifeless. It is an active,

intelligent and conscious energy.  Reiki energy has an innate intelligence and goes wherever

needed in the body and energy field. You can give Reiki treatments to yourself, family,

friends, animals, plants and even machines and can be used for world events.

 During energy healing, the healer conducts universal life energy into the patient, allowing

the overall health of the energy field to be enhanced. Though Reiki flows through the

practitioner but is not generated by the practitioner and does not deplete the Reiki

practitioners own energy supplies. The practitioner is the catalyst that assists the

patient’s own life-force energies to absorb the correct frequencies required.

 Reiki does not often confer an instant miraculous cure of any condition. It helps to

correct body’s disturbed energy pattern, restores energetic balance and repair things like  

blockages and tears in the energy field, which create disease and unhappiness. This can take

time. Patient often gets great advantage from a single treatment but chronic disease may

require consistent treatment for certain period of time.

 What are Attunements ?

Once attuned to Reiki, anyone can access this energy by just intention. It is amazingly

simple techniques transferred to the student by the Reiki Master through the processes are

called attunements or empowerment or sometimes initiations.  Its use is not dependent on

ones intellectual capacity or spiritual development and, therefore, is available to

everyone. It has been successfully taught to thousands of people of all ages and

backgrounds.

It removes blocks in the aura and allows the healing energies that surround us to come in

through our crown chakra and flow through our bodies and out our hands to where they are

needed. They open the palm chakras and energy channels if needed and connect you to the

specific Reiki Shakti healing frequencies. The attunements also allow us to direct these

energies for specific purposes.

 In Usui Reiki there are normally three levels of Reiki designated I, II and Master/Teacher.

In level one people are taught history of Reiki basic techniques for hands on treatment for

self, family, friends, plants, animals, food and water.

 Level two attunes you to dynamic, multi-dimensional energy keys or symbols. These sacred

symbols allow you to access many different levels or dimensions of energy. one learns

Specific techniques of absentee healing.

Level three adds a spiritual or intuitive healing energy function and the ability to attune

others to Use Reiki themselves. Psychic surgery and the making of crystal grids are also

taught at this stage to enable the learner to remove energy blocks. There are different

views concerning the waiting period between the attunements. I personally feel that it is a

matter of personal preference. So we should listen our inner voice and then move on.

Being a Reiki Master is not a sign or guarantee of a person's moral fiber, upstanding

behavior, or any form of spiritual development. Reiki Masters are as human as anyone else.