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"Pranayama is control of Breath" In the body, "Prana" is breath or vital energy. The pranic energy responsible for life or life force is expressed at subtle levels by prana, and "ayama" means power. So "Control of Breath" is Pranayama.
The rhythms of pranic energies can be controlled with pranayama and a balanced body and mind can be attained. In his Yoga Sutras text, Patanjali referred to pranayama as a way of achieving higher states of consciousness, citing the holding of breath as an essential practice of attaining Samadhi. Hatha Yoga also speaks about 8 kinds of pranayama that can be safe for the body and mind.