The word “yoga” is derived from the Sanskrit root yuj which means to yoke, bind or join. Yoga is any practice in which the small “self” of ego is yoked or bound or joined to the larger Self of Spirit (or Tao or Brahman or Purusha or Buddha-Nature or Pure Consciousness or God or whatever).
Neidan and Qigong practices are forms of Taoist Yoga, with origins in China. In the west, the term “yoga” is usually associated with Hindu practices -- and in particular the asanas, i.e. physical postures/movements -- originating in India. There are also forms of Buddhist Yoga, some of which include physical practices similar to Hindu asana practice. The Six Yogas of Naropa are more internal forms of Buddhist Yoga, basically equivalent to Taoist Inner Alchemy Kan & Li practices.
For a beautiful description of the yogic process, have a look at Richard Freeman’s “The Unfolding Mirror of Prakriti.”
