Prana is the Sanskrit for "breath". It is one of the five organs of vitality or sensation, viz. prana "breath", vac "speech", caksus "sight", shrotra "hearing", and manas "thought" (nose, mouth, eyes, ears and mind;).
In Vedantic philosophy, it is the notion of a vital, life-sustaining force of living beings and vital energy, comparable to the Chinese notion of Qi. Prana is a central concept in Ayurveda and Yoga where it is believed to flow through a network of fine subtle channels called nadis.
Nadis
In Yoga, the three main channels of Prana are: the ida, the pingala, and the sushumna. Ida relates to the left side of the body terminating at the left nostril and pingala to the right side of the body terminating at the right nostril. In some practices, alternate nostril breathing balances the prana that flows within the body. When prana enters a period of uplifted, intensified activity, the Yogic tradition refers to it as Pranotthana.