Yoga is a way of life. All yoga schools of thought emphasize the importance of the mind remaining calm, because as the saying goes, only when the water is still can you see through it. It is the result of human wisdom and insight on physiology, psychology, ethics and spirituality collected together and practiced over thousands of years for the well being of humanity.

The basic idea of yoga is to unite the atma or individual soul with the paramatma or the Universal Soul. According to Yoga philosophy, by cleansing one’s mind and controlling one’s thought processes one can return to that primeval state, when the individual self was nothing but a part of the Divine Self. This is the sense encapsulated in the term samadhi. The aim of the yogi is to be able to perceive the world in its true light and to accept that truth in its entirety.

In Sanskrit, the term ‘yoga’ stands for ‘union’. A yogi’s ultimate aim is to be able to attain this ‘union’ with the Eternal Self with the help of certain mental and physical exercises. It is often said that Hiranyagarbha (The Cosmic Womb) Himself had originally advocated the traditional system of yoga, from which all other yoga schools have evolved. But for all extant knowledge of yoga and its practices, such as yogasanas and pranayama, the entire credit goes to Maharishi Patanjali.

Patanjali systematized the various yogic practices and traditions of his times by encapsulating them in the form of aphorisms in his Yoga Sutra. In this momentous work, he describes the aim of yoga as knowledge of the self and outlines the eight steps or methods of achieving it. These are:

• Yamas or eternal vows,
• Niyamas or observances,
• Yogasanas or yoga postures,
• Pranayama or breath control exercises,
• Pratyahara or withdrawal of the senses from distractions of the outside world,
• Dharana or concentration on an object, place or subject,
• Dhyana or the continuance of this concentration-meditation and
• Samadhi or the ultimate stage of yoga meditation.

The collation of these eight steps is known as Patanjali’s Ashtanga Yoga. Source