The second stage or limb of yoga as defined by Patanjali in his Yoga Sutras and is a collection of five observances or personal disciplines. The five niyamas are purity, contentment, self-discipline, self-study, and living with an awareness of the Divine.
the five inner disciplines as preliminaries in Yoga and Tantra
In the Yoga Sutras, Patanjali defined five niyamas or observances relating to inner discipline and responsibility. They are purity, contentment, self-discipline, study of the sacred text, and living with the awareness of God.