Yamas, and its complement, Niyamas, represent a series of “right living” or ethical rules within Hinduism and Yoga. These are a form of moral imperatives, commandments, rules or goals. Every religion has a code of conduct, or series of “do’s and don’ts”, and the Yamas represent one of the “don’t” lists within Hinduism, and specifically, rāja yoga.
Yama (Sanskrit) यम, means self-restraint, self-control and discipline. The yamas comprise the “shall-not” in our dealings with the external world as the niyamas comprise the “shall-do” in our dealings with the inner world.
Ten yamas are codified as “the restraints” and ten niyamas are codified as set of prescribed actions (observances, requirements, obligations) in numerous scriptures including the Shandilya and Varaha Upanishads, the Hatha Yoga Pradipika by Gorakshanatha, and the Tirumantiram of Tirumular. Patañjali lists only five yamas and five niyamas in his Yoga Sūtras.