We associate the term “Prana” with breath. We understand it as the life-force within us. It is this, and much more. While the life-breath is the closest and easiest manifestation of Prana for us to relate to, Prana is not limited to the life-breath. It is a universal force, active in all movement of energy in the universe. The force that moves the galaxies, the force that is active in the atomic realm, are manifestations of the universal Prana. Even our human life-breath is not an independent action, as we are co-dependent with the plant life of the planet. Plants breathe in what humans breathe out. Humans breathe in what plants breathe out. This is one respiration process that is taking place.
Sri Aurobindo notes: “Thus the Prana is vital or nervous force which bears the operations of mind and body, is yoked by them as it were like a horse to a chariot and driven by the mind along the paths on which it wishes to travel to the goal of its desire. … It is in fact that which does all the action of the world in obedience to conscious or subconscious mind and in the conditions of material force and material form. While the mind is that movement of Nature in us which represents in the mould of our material and phenomenal existence and within the triple term of the Ignorance the knowledge aspect of the Brahman, the consciousness of the knower, and body is that which similarly represents the being of the existent in the mask of phenomenally divisible substance, so Prana or life-energy represents in the flux of phenomenal things the force, the active dynamis of the Lord who controls and enjoys the manifestation of His own being. (The three are the reverse aspects of Chit, Sat and Chit-Tapas.) It is a universal energy present in every atom and particle of the universe, and active in every stirring and current of the constant flux and interchange which constitutes the world.”
Sri Aurobindo, The Upanishads, Kena Upanishad and analysis, pg. 102, 156-160