The great ancient exponent of raja yoga Patanjali, more than 2000 years ago wrote in His so called “Patanjali Yoga Sutras” that the path of spiritual enlightenment and perfection embraces eight stages. This path is known as ashtanga yoga or (eight limbed path) or the (eight fold path).
This teaching is scientific and universal. Just as the law of cause and effect or the law of gravity affects everyone in the world equally, so these teachings describe the steps every devotee must go through no matter his nationality, religion, creed, race or belief.
Many people explain these the wrong way, but here is the exact explanation about them of the great yoga master Paramhansa Yogananda
The 8 stages are
Yama is the first of the eight limbs of yoga outlined in the yoga sutras. Yama is also sometimes called “the five restraints” because it describes what the yogi should avoid at all cost in order to advance on the spiritual path.
The 5 restraints are;
The first part of the yamas is called Ahimsa or non-violence or harmlessness. This cannot always be practiced literally since it is not always possible in the normal course of living. Even when washing your hands you kill bacteria. Rather perfect ahimsa is achieved through inward desire TO NOT cause harm in any creature or living being. As Yogananda uased to say; “God reads the heart”
Satya is non-lying or truthfulness. This doesn’t mean to be tactless, but to always tell the highest truth. It is in the “restraints” category because if one restrains oneself from wishing things were other than they are, one will always tell the truth.
Asteya means non-covetousness. Not wishing for more than one has, or for what another has.
Brahmacharya is sexual self-restraint. Literally means “flowing with Bramha.” This is often translated as celibacy, but can also just be taken as sexual self-control, or overcoming sexual desire. According to the yoga sutras, this practice will give one great mental and physical stamina because it prevents one’s energy from being expended in sexuality. Self-control in all things is the direction of true growth.
This means non-possessiveness. Letting go of all attachment to one’s possessions, including one’s body, and being willing to relinquish them all at a moment’s notice.
Niyama are the second stage and it lists the five things the yogi must do if he wants to make steady spiritual progress.
Saucha means cleanliness of the body, mind, and heart. When ones body and mind are clean the energy can flow freely without obstruction. Dirty or polluted body and mind stagnates the energy and attracts lower astral entities who can harm and obstruct the spiritual progress of the aspiring yogi.
Santosha means contentment. To attain this the yogi must realize that nothing in this material world can make him really happy. He knows that he will find the eternal bliss he is looking for in only in his own higher Self.
Tapasya is austerity or self-restraint. This does not mean harming or depriving oneself of essential needs (which would violate the first yama, ahimsa). Tapasya is essentially self-discipline and not self-harm. Without tapasya one cannot achieve anything meaningful not only ion yoga but in any other endeavor.
Swadhyaya is self-study or introspection. This is sometimes translated as “study of the scriptures,” but the literal meaning is “Self-study,” or study of the Higher Self. To achieve this niyama, one should always question one’s motives and reasoning, and stay open to the possibility that one could be wrong.
Worship of the Supreme Lord
Asana is the third limb on of the path that Patanjali defined. It does not mean hatha yoga postures, but the ability to sit unmoving with a straight spine in meditation for long periods of time. The hatha yoga postures can only help the yogi to be able to do this.
Pranayama means control over energy in the body. If one can control one’s energy, then one can withdraw it from the outer senses and up the spine, thereby raising one’s consciousness.
Pratyahara is the interiorization of the attention and the thoughts in meditation
Dharana is concentration; one-pointed focus.
Dhyana means steadfast meditation on God.
Samadhi is complete absorption in the infinite — literally “oneness.” Infinite bliss.