The Yoga Sutras is a scripture of 196 sutras (written) by Sage Patanjali. The word sutra means “thread” and implies that the written words carry an underlying continuous thought. The various ideas connect like the beads on a mala to form a complete philosophy.

The scripture is regarded as the most precise and scientific text written on yoga, and it is a masterpiece of brevity and clarity.
There is no certainty about Patanjali’s time, but a widely accepted date is about 400 years before Christ.
The scripture is divided into four chapters:

1. Samadhi Pada
2. Sadhana Pada
3. Vibhooti Pada
4. Kaivalya Pada

Sage Patanjali called his system yoga without any specific title; however, his method has become Patanjali yoga.
Patanjali gives a wide range of techniques that slowly harmonize the mind and gradually induce a more subtle perception. However, the main path of Patanjali is contained with eight fundamental stages as discussed in the Sadhana Pada.

The first five stages are:
1) Yama (social code)
2) Niyama (personal code)
3) Asana (sitting posture)
4) Pranayama (control of prana)
5) Pratyahara (withdrawal of sense)

These first five stages are the exoteric or bahiranga, external, practices of yoga. They progressively prepare the body-mind for the last three stages:

6) Dharana (concentration)
7) Dhyana (meditation)
8) Samadhi (super consciousness)

The last three stages are the esoteric or antaranga, internal, practices of yoga.
The stages up to pratyahara gradually remove external distractions, while the practices from dharana onwards eradicate the disturbing thoughts and psychic manifestation so that the mind ceases to function. The first five stages negate consciousness, while the last three expand consciousness. The more advanced stages can only be practiced successfully after the prior practice of the earlier preparatory stages.

In a little more detail, the five yamas are satya, truthfulness; ahimsa, feeling of non-violence to all things, human, animal; asteya, honesty; brahmacharya, sexual control or abstinence, and aparigraha, non possessiveness.
The niyamas are also five in number: shaucha, cleanliness; santosha, contentement; tapah, austerity; swadhyaya, self-study, and Ishwara pranidhana, surrender to the cosmic will.

The yamas are designed to harmonize one’s social interactions and the niyamas are intended to harmonize one’s inner feelings. All the rules, yamas and niyamas, are designed to reduce friction between outer actions and attitudes. The yamas and niyamas aim to break this vicious circle and thereby calm the mind by sensible actions and sensible attitudes towards oneself, one’s life, and one’s surroundings.

Asana in this system is a steady and comfortable sitting position such as padmasana and siddhasana.
Pranayama is to concentrates all the pranic forces of the human structure.

These techniques lead to control and one-pointedness.
Pratyahara means “to gather inwards”. This practice is concerned with turning the attention and awareness inward without being distracted by external sense experience.
Dharana means concentration of the mind. It is the step before meditation and is concerned with fixing awareness on one object to exclude all others.
Dyana is merely an extension of dharana that eventually leads to an elimination of duality: the seer, seen, and seeing merge into a unity, and one fuses into the state of samadhi.
Samadhi is the state where there is the complete absence of both external and internal mental modification; all that remains is awareness