Ashtanga yoga (Sanskrit: अष्टाङ्गयोग, romanized: aṣṭāṅgayoga[1], "eight limbs of yoga") is Pātañjali's classification of classical yoga, as set out in his Yoga Sūtras. He defined the eight limbs as yama (abstinences), niyama (observances), āsana (postures), prāṇāyāma (breath control), pratyāhāra (withdrawal of the senses), dhāraṇā (concentration), dhyāna (meditation), and samādhi (absorption).
The eight limbs form a sequence from the outer to the inner. The posture, asana, must be steady and comfortable for a long time, in order for the yogi to practice the limbs from prāṇāyāma until samādhi. The main aim is kaivalya, discernment of Puruṣa, the witness-conscious, as separate from Prakṛti, the cognitive apparatus, and disentanglement of Puruṣa from its muddled defilements.