Ashtanga yoga is an ancient system of yoga brought to wide knowledge by Sri Krishna Pattabhi Jois (1915 - 2009), who learned the system from his guru Krishnamacharya. Literally Ashtanga yoga means eight limbed yoga as described in the Yoga Sutras of Patanjali. The eight limbs are yama, niyama, asana, pranayama, pratyahara, dharana, dhyana and samadhi. The first four limbs (ethical guidelines, posture and breath control) can be practiced externally, whereas the latter four are internal and arise spontaneously as a result of an established practice.
Pattabhi Jois encouraged to start the practice from asana (posture) practice. Asana practice is important as it brings stability to both body and mind and prepares the practitioner for other, more subtle aspects of yoga. It purifies and strengthens the body, calms the mind and generates health and an overall sense of well-being.
The main components of asana practice are vinyasa (breathing and movement system), tristhana (three places of attention: posture, breathing system and gazing point (drishti)). Mula and udiyana bandhas (anal and lower abdominal locks) are important components of the breathing system.
Over time, Ashtanga yoga practice brings forth clarity and peace of mind. A continuous practice done with dedication and diligency leads to internal purification, and gradually clears off the obstacles to realizing one's true Self.
Read more: http://kpjayi.org/the-practice