Yoga is a physical, mental, and spiritual discipline, originating in ancient India. The goal of yoga, or of the person practicing yoga, is the attainment of a state of perfect spiritual insight and tranquility while meditating on super soul. The word is associated with meditative practices in Hinduism, Jainism and Buddhism. The Sanskrit word yoga has the literal meaning of "yoke", from a root yuj meaning to join, to unite, or to attach. As a term for a system of abstract meditation or mental abstraction it was introduced by Patañjali in the 2nd century BC. Someone who practices yoga or follows the yoga philosophy with a high level of commitment is called a yogi or yogini. The heart of any yoga practice is the performance of yoga positions (called asanas), each of which has specific physical and mental benefits. Asana is defined as "posture;" its literal meaning is "seat." Originally, the asanas served as stable postures for prolonged meditation. Pictures below are some of extreme poses in yoga.