Yoga sutra 2.29 states, Yama niyamasana pranayama pratyahara dharana dhyana samadhi astau angani: The eight limbs of yoga are: yama (self-regulation), niyama (observances), asana (posture), pranayama (breath control), pratyahara (withdrawal of senses), dharana (concentration), dhyana (meditation), and samadhi (bliss).
The eight limbs of yoga establish practical guidelines for the complete practice of yoga. The rungs, or limbs, are designed to be practiced concurrently, not stepwise. Like the limbs of a tree all growing at the same time, the eight limbs of yoga are practiced together. The eight limbs can be separated, however, into those limbs that involve action, and those limbs that are the result, or reaction.
The yamas and niyamas establish the ethical guidelines for self-conduct and conduct with the world around us. They set the backdrop for a more meaningful life and are a daily part of a yogi’s life. Asana, pranayama, and pratyahara are best combined within the context of a physical practice. Postures, along with proper breathing and withdrawal of the senses, help to bring the body and mind into a calmer state so that concentration (dharana) and meditation (dhyana) can arise, leading to, eventually, samadhi, the ultimate state of meditative bliss.
Asana, or the familiar physical posture practice common in the West, is just one rung of this complete practice. When fully integrated, the eight limbs of yoga, also called Ashtanga Yoga and Raja Yoga, prepare us to transcend our suffering and understand our true nature, as experienced in the state of samadhi.