Yoga refers to traditional physical and mental disciplines originating in India. The word is associated with meditative practices in both Buddhism and Hinduism. In Hinduism, it also refers to one of the six orthodox (astika) schools of Hindu philosophy, and to the goal toward which that school directs its practices.
Major branches of yoga include Raja Yoga, Karma Yoga, Jnana Yoga, Bhakti Yoga, and Hatha Yoga. Raja Yoga, compiled in the Yoga Sutras of Patanjali, and known simply as yoga in the context of Hindu philosophy, is part of the Samkhya tradition. Many other Hindu texts discuss aspects of yoga, including the Vedas, Upanishads, the Bhagavad Gita, the Hatha Yoga Pradipika, the Shiva Samhita and various Tantras.
The Sanskrit word yoga has many meanings, and is derived from the Sanskrit root yuj, meaning "to control", "to yoke" or "to unite". Translations include "joining", "uniting", "union", "conjunction", and "means". Outside India, the term yoga is typically associated with Hatha Yoga and its asanas (postures) or as a form of exercise. An accomplished practitioner of Yoga is called a Yogi (gender neutral) or Yogini (feminine form).
Interested in how Yoga Trends change?World Wide Study on Yoga Trends from 2004 through 2011