प्राण Prana: breath of life, breath, filled, old, full, ancient, spirit, vitality, energy, wind, spirit, respiration, spirit identified with the totality of dreaming spirits, poetical inspiration, vigour, life, power, air inhaled, vital organ, vital air, myrrh
Prana is energy. Prana is Christ. That energy is the energy that palpitates in the heart of every existing thing. Everything: every rock, plant, fish, horse, planet, sun, universe, sun, is sustained by the fire of Christic Prana. That is why Christ is “the life, the light, and the way.” It is the energy of existence. It is the Ain Soph Aur. That prana, that energy vibrates in many different modalities, many different levels of existence, and it is what sustains everything. It is the great breath. Everything that is in you is prana, in different modifications. We live, we breathe, we exist, we are sustained by that force.
Prana is the sum total of all energy that is manifest in the universe. It is the sum total of all the forces in nature. It is the sum total of all latent forces and powers which are hidden in men [and women] and which lie everywhere around us. Heat, light, electricity, magnetism are the manifestations of prana. […] Whatever moves or works or has life is but an expression of manifestation of prana. The prana is related to mind [Hod/Netzach] and through mind to will [Tiphareth], and through will to the individual soul [Tiphareth/Geburah], and through this to the Supreme Being [Chesed/ Atman]. If you know how to control the little waves of prana working thorough your mind, then the secret of subjugating universal prana will be known to you. The Yogi who becomes an expert in the knowledge Of this secret, will have no fear from any power, because he has mastery over all the manifestations of powers in the universe. What is commonly known as power of personality is nothing more than the natural capacity of a person to wield his Prana. Some persons are more successful in life, more influential and fascinating than others. It is all due to the power of this Prana. Such people manipulate everyday, unconsciously of course, the same influence which the Yogi uses consciously by the command of his will. There are others who by chance tumble unaware of this Prana and use it for lower purposes under false names. Prana is not separate from us. It is not a concept. Prana is not a theory. Everything that exists is prana, but modified by cause and effect (karma). The development of the soul is a modification of prana. The creation of Bodhichitta is a perfection of Prana. When the Bodhi mind, the Christ mind, is emerging in the psyche, it is the ray of creation itself, harnessed, modified, and expressed through us. That is what Prana is. The beginning of that, the harnessing of that, is called by another name: Kundalini. We are going to talk about what that means. This word Prana is Sanskrit. The Tibetan word is lung. These are two words from different languages that describe the same thing. In English, we can call it energy. For us, when we think of energy we tend to think of things that are materialistic, like electricity. Yet, prana is a type of energy is not limited by physical matter. Prana or lung is in every dimension, not just the third dimension. Prana or lung is the very reason the third dimension exists, but it is not third dimensional. Moreover, it is not merely fourth dimensional, it is not merely fifth dimensional, or sixth or the zero dimension, the seventh. Prana or lung can also be translated as “wind.” Not physical air, not wind like physical air, but wind like a flowing of energy, a flow of forces we cannot see physically, but we can feel it. Like physical wind, you can feel it, but you cannot see it. Prana is the same way. You can feel it, but you cannot see it with your physical eyes. You can see it with clairvoyance, but not with your physical eyes. Prana descends down through all the levels of creation. Prana is the root energy of everything that we are. Every thought that we have is a vibration or a modification of Prana. Our internal bodies are forms of Prana in their respective levels of nature. Our willpower, our Consciousness, or our essence or spark of soul, is related in the fifth dimension with the Sephiroth Tiphereth, what we call the human soul or the essence. In Sanskrit, this is called Buddhadatu. It is also called Tathagatagarbha. This means embryo of soul, or Buddha nature. We all have this Buddha nature. It is a seed; it is a germ in which the archetypes of soul are placed. Those archetypes are then impregnated into Mother Nature so that seed can grow. Any seed in nature needs nourishment. Every seed. Especially the seed of our soul. This working of Prana is seen in the systolic and diastolic actions of the heart, when it pumps the blood into arteries in the action of inspiration and expiration during the course of breathing; in the digestion of food; in the excretion of urine and faecal matter; in the manufacture of semen, chyle, chyme, gastric juice, bile, intestinal juice, saliva; in closing and opening of the eyelids, in walking, playing, running, talking, thinking, reasoning, feeling and willing. Prana is the link between the astral and physical body. When the slender thread-link Prana is cut off the astral body separates from the physical body. Death takes place. The Prana that was working in the physical body is withdrawn into the astral body.
Seat of Prana
The seat of Prana is heart. Though the Antakarana is one, yet it assumes four forms, (i) Manas, (ii) Buddhi, (iii) Chitta and (iv) Ahamkara according to the different functions it performs. Likewise, though Prana is one, it assumes five forms viz., (1) Prana, (2) Apana, (3) Samana, (4) Udana and (5) Vyana according to the different functions it performs. This is termed as Vritti Bheda. The principal Prana is called Mukhya Prana. The Prana, joined with Ahamkara, lives in the heart. Of these five, Prana and Apana are the chief agents. The seat of Prana is the heart; of Apana, the anus; of Samana, the region of the naval; of Udana, the throat; while Vyana is all-pervading. It moves all over the body.
Channels of Prana
According to the system of yoga, vital life force called prana courses through the human body by means of a network of minute conduits or canals known as nadis. This psycho-physical circuitry is often called the “subtle body.” In yoga, the physical body is refined not simply for its own sake, but in order that it may serve the subtle body. The main nadi or conduit is called the sushumna, which runs from the bottom of the spine to the top of the cranium. Along its length, the sushumna connects the seven chakras or main energy centers. Many more chakras are said to exist within the body, but all are governed by the primary seven.
The two other important nadis are known as the ida and the pingala. They start at the base of the spine and wind around the sushumna like strands of DNA. The ida ends at the left nostril and is associated with the moon and the left side of the body. The pin- gala terminates at the right nostril and corresponds to the sun and the right side of the body. These two nadis take in prana from the surrounding environment, and they are important to the practice of pranayama or the discipline of breath control. The ability to control breathing is equated with the ability to control the amount of prana retained in the body. In this way, the revitalizing prana energy can be fully utilized to the benefit of the practitioner.
This diagram is from a Tibetan medical treatise. It shows subtle channels
If we are sensitive, we can feel these energies. We use them every day. We use them all of the time. There is nothing supernatural about this. It is perfectly normal, but what is abnormal is that we are ignorant of it. We have our noses buried in the dirt, digging for garbage like pigs, trying to suck up desires, feed our fears and lusts, instead of being concerned with the qualities of the spirit. If we pay attention, we can experience what these Nadis are, we can learn how they work, and we can learn how to use them effectively to help other people. The word Nadi means channel or conduit and comes from the root nad, which means movement. That movement is related to Prana. When we look at the Nadis or any kind of diagram — whether it is Tibetan or Chinese or Hindu diagram — what these channels and conduits show is how energy moves. It shows how prana moves through us. There are the two nerve-currents one on either side of the spinal column. The left one is called Ida and the right is known as Pingala. These are Nadis. Tentatively, some take these as the right and the left sympathetic cords, but they are subtle tubes that carry Prana. The Moon moves in the Ida and the Sun in the Pingala. Ida is cooling. Pingala is heating. Ida flows through the left nostril and the Pingala through the right nostril. The breath flows through the right nostril for one hour and then through the left nostril for one hour. Man is busily engaged in worldly activities, when the breath flows through Ida and Pingala. When Sushumna operates, he becomes dead to the world, and enters into Samadhi. A Yogi tries his level best to make the Prana run in the Sushumna Nadi, which is known as the central Brahman Nadi also. On the left of Sushumna is situated Ida and on the right is Pingala. The moon is of the nature of Tamas and the sun is that of the Rajas. The poison share is of the sun and the nectar is of the moon. Ida and Pingala indicate time. Sushumna is the consumer of time. Sushumna is the most important of all the Nadis. It is the sustainer of the universe and the path of the universe and the path of salvation. Situated at the back of the anus, it is attached to the spinal column and extends to the Brahmarandhra of the head and is invisible and subtle. The real work of a Yogi begins when Sushumna begins to function. Sushumna runs along the centre of the spinal cord or spinal column. Above the genital organs and below the navel is the Kanda, of the shape of a bird’s egg. There arise from it all the Nadis 72,000 in number. Of these, seventy-two are common and generally known and Of those the chief ones are ten and they carry the Pranas. (1) Sushumna, (2) Ida, (3) Pingala, (4) Gandhari, (5) Hastijihva, (6) Kuhuh, (7) Saraswati, (8) Pusha, (9) Sankhini (10) Payasvini, (11) Varuni, (12) Alambusa,(13) Vishvodhara and (14) Yusasvini are said to be the 14 important Nadis. Whenever there is an interlacing of several nerves, arteries and veins, that centre is called “Plexus.” The physical material plexuses that are known to the Vaidya Shastra are:— Pampiniform, Cervical, Brachial, Coccygeal, Lumbar, Sacral, Cardiac, Esophageal, Hepatic Pharyngeal, Pulmonary, Ligual Prostatic Plexus, etc. Similarly there are plexuses or centres of vital forces in the Sukshma Nadis. They are known as ‘Padma’ (lotus) or Chakras. All the Nadis spring from the Kanda. It is in the junction where the Sushumna Nadi is connected with the Muladhara Chakra. The Yogis should have a knowledge of the Nadis and the Chakras. Ida, Pingala and Sushumna are said to carry Prana and have Moon, Sun and Agni as their Devatas. When Prana moves in Sushumna, sit for meditation may reach deep Dhyana. If the coiled-up energy, Kundalini, passes up along the Sushumna Nadi and is taken up from Chakra to Chakra the Yogi gets different sorts of experiences, powers and Ananda. Prana energy, does not move just physically but It is moving through all the different aspects of our psyche. When we look at the top level of Tree of Life, we have the Prana; which is descending from above. These upper levels relate to Archetypal levels, related to the Innermost, and uppermost parts of our Being. 
The Five Pranas
“The flow of the “prana” currents in the body is the same as the energy of the sun acting in Nature as a whole and is needed by every cell for its function and life in the human body. This “prana” function is the real physiology, because it supports all sensory and motor functions in the body. “Prana” is the river of life, as the vital current of the body, in its five-fold action. It is the distributor of the Life Force throughout the body. The “tattwas” (elements of earth, water, fire or warmth, air and ether) are the fields and structural tissues of anatomy. They support the “life winds” of “prana” that flow through the house we live in and call our body, the temple of Being on this earth.” – Randolph Stone
The Kundalini is Divine static and dynamic energy. The static energy (Kundalini), is sleeping at the Muladhara (Root Chakra); the dynamic energy of the Kundalini is all over the body as Prana, Apana, Samana, Vyana, and Udana. These five Vital breaths, or life forces, keep the body together. The duties of the five Pranas are as follows: Prana remains in the upper part of the body, and always moves upward; the Apana resides in the lower part of the body, or abdomen, and always flows downward; the Samana stays in the first section of the torso, digesting and distributing the food substances; the Vyana resides in the heart, and from there moves all over the body, its duty being the circulation of the blood; the Udana carries the Soul upward when the body dies. These five Pranas stay in the grosser body. They are also in the finer or subtle body—the five finer breaths corresponding to the five grosser Pranas above described. The Pranayama Yoga, the Mudra Yoga, and Dharana Yoga, are all for the control of the five Pranas and mind. Mind without Prana is like a bird without wings. The practice of the Mudras is to control the dynamic energy of the Kundalini, namely, Prana, Apana, etc. The practice of Pranayama is also to control the Prana, Apana, etc.—the dynamic energy of the Kundalini, and with it awaken the static energy of the Kundalini, which is sleeping at the Muladhara, or root Chakra. When the five Pranas are controlled or made to stop at the desired place, the Muladhara Chakra, or at the door of the Sushumana, it will work like a spark to the static energy of the Kundalini.
“When Prana and Apana are mixed, it will naturally cause heat in the body; then the body becomes light and powerful. This extreme heat when felt by the Kundalini, causes her to awaken from sleep. Then she goes into the Sushumana.” (From H. Y. P.)
The duty of the Yogi is to gather together or control the five Pranas—the life force of the Kundalini—that the dynamic energy of the Kundalini may be used to awaken the static energy of it, as one Kundalini energy will move the other energy. 
B.k.S Iyengar in his book “Light on Yoga” describes the fivefold function of prana briefly as follow:
“Prana Vayu. One of the most subtle forms of energy is air. This vital energy which also pervades the human body is classified in five main categories in the Hatha Yoga texts according to the various functions performed by the energy. These are termed vayu (wind) and the five main divisions are: Prana (here the generic term is used to designate the particular), which moves in the region of the heart and controls respiration; Apana, which moves in the sphere of the lower abdomen and controls the function of eliminating urine and feces; Samana, which stokes the gastric fires to aid digestion; Udana, which dwells in the thoracic cavity and controls the intake of air and food; and Vyana, which pervades the entire body and distributes the energy derived from food and breath. There are also five subsidiary vayiis. These are: Naga, which relieves abdominal pressure by belching; Kurma, which controls the movements of the eyelids to prevent foreign matter or too bright a light entering the eyes ; Krkara, which prevents substances passing up the nasal passages and down the throat by making one sneeze or cough; devadatta, which provides for the intake of extra oxygen in a tired body by causing a yawn, and lastly dhanariljaya, which remains in the body even after death and sometimes bloats up a corpse.”
Articles on Prana