Reiki (pronounced ray-key) is a Japanese stress reduction and relaxation technique that promotes healing. Reiki is administered from the hands and can be done with a hands-on or hands-off approach to the body during a session.
It is important to note that before Usui Reiki, there were four different types of Reiki healing systems in Japan. Reiki was a healing art even before Usui himself discovered and founded his style, Usui Reiki Ryoho. This version has become the most commonly known Reiki.
While trying to discover his life purpose and seek a spiritual state of unwavering peace, Usui encountered this healing energy in Kurama Yama while fasting and meditating.
He would later refine this energy as Reiki and eventually move to Tokyo to open a clinic where he would teach classes and give treatments.

The term 'Reiki' is derived from the beautiful script of Japanese kanji, a nuanced and multi-layered form of written language. Specifically, 'Reiki' is a combination of two distinct kanji, 'Rei' and 'Ki'. It's important to remember, when interpreting kanji, the context is key, as these ideograms can embody a multitude of meanings. These particular kanji, when used in a spiritual setting, carry an essence that transcends a simple translation from Japanese to English. They hold a depth and richness that only truly unfolds within their intended spiritual framework.

Rei can be described as the Higher Intelligence that guides the creation and functioning of the universe. It embodies a subtle wisdom that flows through all things, both living and non-living. This essence directs the evolution of all creation, from the formation of galaxies to the emergence of life. On a personal level, Rei offers support during challenging times and serves as a guiding force in our lives. Due to its boundless nature, it possesses all-encompassing knowledge. Often referred to as God, Rei is recognized by many other names across different cultures.

Ki is the intangible energy that enlivens all living beings. It flows through everything that is alive, including plants, animals, and humans. When a person's Ki is abundant, they tend to feel strong, confident, and eager to embrace life's challenges. Conversely, low Ki can lead to feelings of weakness and a higher susceptibility to illness. We draw Ki from the air we breathe, the food we consume, the sunlight we absorb, and the rest we get from sleep. Additionally, engaging in breathing exercises and meditation can help boost our Ki levels. When a person passes away, their Ki departs from the physical body. Ki is also recognized as Chi in China, prana in India, and Ti or Ki in Hawaiian culture, and it has been referred to as odic force, orgone, bioplasma, and life force.

“Reiki can be defined as a non-physical healing energy made up of life force energy that is guided by the Higher Intelligence or spiritually guided life force energy. This is a functional definition as it closely parallels the experience of those who practice Reiki in that Reiki energy seems to have an intelligence of its own, flowing where it is needed in the client and creating the healing conditions necessary for the individual’s needs. It cannot be guided by the mind, therefore, it is not limited by the experience or ability of the practitioner. Neither can it be misused as it always creates a healing effect. ( It must be kept in mind that Reiki is not the same as simple life force energy as life force energy by itself can be influenced by the mind and, because of this, can create benefits as well as cause problems, including ill health.)”
Lee Rand, Reiki Energy, Reikienergy,org

Usui Reiki, its’ Meaning, and Brief History of the Founder.