Can refer to energy, life, or breath. In other traditions it is called chi or qui. (1)
Prana is the universal sea of energy that infuses and vitalizes all matter. This sea of energy coalesces into sub-atomic particles and atoms, which become the basic building blocks of all matter manifesting the physical world. So, every atom, molecule, and cell is an extension of prana, just as waves are extensions of the sea that lies beneath them. (1)
Prana is also the power that flows in all living forms and performs vital functions. Paramhansa Yogananda called this aspect of prana “life-force.” He further explained that life-force possesses an inherent intelligence enabling it to carry out the life-sustaining processes.
To give clarity to this image, he even coined the term “lifetrons.” We have a subtle or astral body made up of prana that underlies the physical body. Oriental healing techniques, such as Ayurveda and acupuncture, work to harmonize and strengthen the flow of life-force, calling it variously prana, chi, or ki. When the life-force flows properly, the result will be a natural state of health and vitality. (1)
Prana is also used to refer to the breath. When we take a physical breath, there is a corresponding movement of prana in the subtle or astral spine. Prana flows up in the subtle spine in conjunction with the inhalation, and down with the exhalation.
This link between breath and the flow of prana is central to many of the techniques of meditation. By controlling the breath, which is easily felt, we can influence the flow of prana, which is much more subtle and difficult to feel. (1)
Pranayama (prana = energy + yama = control) is a type of meditation technique that involves various ways of controlling the breathing (1), with the goal being to raise one’s prana (also called Kundalini in this case) up the deep spine to the spiritual eye or sixth chakra, which brings one to enlightenment. Kriya Yoga is one such technique, made well known by Paramhamsa Yogananda in Autobiography of a Yogi. (2)
How Pranayama Works
The prana or energy travels upward through the ida nadi. With this upward movement, the breath is automatically drawn into the lungs. As a result, the mind is drawn outward to the world of the senses.
The energy then travels downwards through the pingala nadi. When the energy is going down, it is called apana rather than prana. This downward movement is accompanied by physical exhalation, and signifies a rejection of external circumstances.
One manifestation of this cycle is the association of inhalation with excitement and happiness, and exhalation with defeat and depression. Happiness and sadness must always follow each other when the cause of each is external circumstances, which are always changing.
However, through pranayama techniques a person can instead redirect the energy through the deep spine in between the ida and pingala, called the sushumna. When the level of energy in the sushumna reaches the top of the spine and goes into the spiritual eye, or sixth chakra, one becomes enlightened. (2)