The term kriyā yoga has a technical meaning in the Yoga Sutras. It designates the "practical" aspects of the philosophy that is the "union with the Supreme" due to performance of duties in everyday life.Kriya Yoga is described by its practitioners as the ancient Yoga system revived in modern times by MahavatarBabaji through his disciple LahiriMahasaya.

Kriya Yoga was brought to the international awareness by ParamahansaYogananda's book Autobiography of a Yogi and through Yogananda's introductions of the practice to the west from 1920. Kriya yoga system consists of a number of levels of pranayama, mantra, and mudra based on techniques intended to rapidly accelerate spiritual development and engender a profound state of tranquillity. Yogananda attributes his description of Kriya Yoga to his lineage of gurus, Sri YukteswarGiri, LahiriMahasaya, and MahavatarBabaji.

Essence of Kriya
Fundamentally kriya means internal action of the body. Both the body and the mind are external to a person. Only when a person develops mastery to do action with his energy, then it is called kriya. Karma (fate) binds a person while kriya releases him. A person’s thoughts and emotions are not stable. They keep fluctuating from time to time but energies are different. If the energies are touched and activated, it gives a completely different dimension to every aspect of life.

Without guidance, the path of Kriya should not be followed as that would be too strenuous and the true essence of Kriya will not be understood. Kriya helps a person to comprehend the essence of life and realization. The Kriya Yogi mentally directs his life energy to revolve, upward and downward, around the six spinal centers (medullary, cervical, dorsal, lumbar, sacral, and coccygeal plexuses) which correspond to the twelve astral signs of the zodiac, the symbolic Cosmic Man.

Potency of Kriya Yoga
Kriya yoga is a very powerful way to walk the spiritual path, but at the same time it is a very demanding way. What it demands out of a person is so tremendous. For a modern educated person today, kriya yoga would be inhuman because it needs that kind of discipline and and certain exactness about everything. Constantly seeking comfort is a hindrance in the path of Kriya. This yoga is important to do things beyond realization. Kriyas are elaborate and involve a lot of discipline and focus.

History
According to Yogananda’s book in ‘God Talks with Arjuna: The Bhagavad Gita’, the science of Kriya Yoga was given to Manu, the first man according to the Vedas. Through him, it passed to Janaka and other royal sages. According to Yogananda, Kriya Yoga was well known in ancient India, but was eventually lost, due to priestly secrecy and man’s indifference. Kriya entails several acts that have evidently been adapted from the Gita, the Yoga Sutras, Tantrashastras and from conceptions on the Yugas.Through LahiriMahasaya, Kriya Yoga soon spread throughout India. Yogananda, a disciple of Sri YukteswarGiri who was himself a disciple of LahiriMahasaya, then brought Kriya Yoga to the United States and Europe during the 20th century. LahiriMahasaya's disciples included his sons, DukouriLahiri and TinkouriLahiri, Sri YukteswarGiri, and many others.

Benefits of Kriya Yoga
By the practice of the scientific technique of Kriya Yoga, simultaneous development of body, mind, intellect and soul takes place. By magnetizing the spine by a very simple way of Kriya practice, one can perceive the all-accomplishing divine energy in the body.

Spiritual Growth
By the practice of the scientific technique of Kriya Yoga, the entire human system is magnetized and energized in a very short time. All the internal organs like liver, pancreas, spleen, thyroid, pituitary, pineal organs are activated. They secrete necessary hormones and enzymes to keep the body healthy.

Mind Control
By the practice of Kriya Yoga, the mind becomes in a short time calm, quiet and thoughtless. The blood absorbs a better quantity of oxygen and becomes quickly de-carbonized, which increases the general well-being. A number of psychosomatic diseases can be avoided.

Intellectual Development
Through more circulation in the head, thereby energizing the brain cells, the working capacity of the brain is enhanced. One will not get easily tired, and the memory and retentive quality of the brain will increase.

Personality Development
Kriya Yoga brings change in the entire human personality, making one free from falsehood and all negativity, and constantly absorbed in truth and divinity.

Kriya Yoga enables constant soul-awareness, in every breath, in every thought and every moment. It quickens spiritual evolution and takes one to the door of spiritual realization in a short time. However the necessary precondition is to practice the technique with love, regularly and sincerely with implicit faith on God and guru.

Few words cannot explain or highlight the immense benefits of this marvellous technique of Kriya Yoga. The real path is perceived by the one who follows it, practices it and realizes too.