yama, (Sanskrit: “restraint”), in the Yoga system of Indian philosophy, first of the eight stages intended to lead the aspirant to samādhi, or state of perfect concentration. An ethical preparation, meant to purify the individual, yama involves the abstinence from injury to others and from lying, stealing, sex, and avarice.
The second stage, niyama (Sanskrit: “discipline”), in its ethical intent similar to yama, comprises five categories of observance: cleanliness, contentment with one’s material condition, asceticism, study of the metaphysics relating to salvation, and devotion to God.
Neither yama nor niyama is a specifically Yogic state; they are preliminaries necessary for any type of asceticism. They prepare the yogic practitioner for the more difficult stages.