The Swamis and gurus observed the animals the birds and other creatures on earth how they are adept in some skills and they tried to copy those asanas and experimented on themselves. Fro there all these asanas came into picture. previously there were 84 lakh Asanas now only few asanas we know and rest all lost in scriptures.
A yogasana is a posture in harmony with one`s inner consciousness. It aims at the attainment of a sustained and comfortable sitting posture to facilitate meditation. Asanas also help in balancing and harmonizing the basic structure of the human body, which is why they have a range of therapeutic uses too.

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Functions of Yogasanas
Asanas basically perform five functions:

• Conative,
• Cognitive,
• Mental,
• Intellectual and
• Spiritual.

Conative action is the voluntary exercise of the organs of action. The asanas being the main yogic instrument of balancing the body, they consist of various physical postures, which are designed to release tension, improve flexibility and maximize the flow of vital energy. The purpose of the asanas is to create a flow of positive energy so that our concentration is directed within ourselves and the mind is able to perceive (parokshya jnana) the effects of our purposive action. That is cognitive action.

When the earlier two actions are fused, our mind`s discriminative faculty guides these organs to perform the asanas more correctly. The resultant rhythmic energy flow and awareness leads to a mental state of pure joy (ananda). Physical postures, therefore, end up affecting the various interrelated channels (nadis) of the mind-body complex. And ultimately the performance of a perfect yogasana leads to the absolute intellectual absorption of the mind on a single task (dharana), which in turn leads to the fusion of the individual spirit with the Divine Self (dhyana).

Benefits of Yogasanas
The regular practice of yogasanas has an immense amount of therapeutic value. Besides various physiological benefits, they positively affect our minds, our life force energies as well as our creative intelligence.

Regular practice helps to keep our body fit, controls cholesterol level, reduces weight, normalizes blood pressure and improves heart performance. Physical fitness thus achieved leads to reduction of physical stress and greater vitality. Asanas harmonize our pranic ability and mental energy flow by clearing any blockages in the subtle body leading to mental equilibrium and calmness. They make the mind strong thus enabling our human body to suffer pain and unhappiness stoically and with fortitude.

Various Categories of Yogasanas
Consummate mastery over the entire gamut of asanas is no doubt time-consuming, but what is of vital importance is the will to remain in the present moment and to let both the mind and body relax completely.

The various categories of asanas are:

• Pawan Muktasana,
• Standing Asanas,
• Forward Bending Asanas,
• Supine Asanas,
• Inverted Asanas,
•Twisting Asanas,
• Back Bending Asanas, and
• Balancing Asanas.

PawanMuktasana: This is the preliminary series of Asana. Pawanmuktasana is very useful as ap starting practice as it opens all the major joints and relaxes the muscles of the body. it should be practiced with interest.

Standing Asanas:
Beginners should start with these as they bring elasticity in joints and muscles and build up stamina and physical stability. This constitutes the most basic training in the early stages of yoga practice. Some basic standing poses are, Tadasana, Utthita Trikonasana, Virabhadrasana, Ardha Chandrasana and Utthita Parsvakonasana.

Forward Bending Asanas:
In these postures the posterior half of the body is stretched. These prepare you to proceed further in yoga and bring consistency in the development of physical and mental pliability. Examples of such asanas are, Upavisthakonasana and Paschimotanasana.

Sitting and Supine Asanas:
Sitting upright and supine extending positions help a sadhaka prepare physically and mentally for pranayama. Some of them are, Baddhakonasana, Supta Baddhakonasana, Supta Padangusthanasana, Padmasana, Vajrasana, Simhasana, Virasana and so on.

Inverted Asanas:
These help recover from everyday stress. They give vitality, mental balance and emotional stability. These are Adho Mukha Svanasa and Urdhva Mukha Svanasa.

Twisting Asanas:
It consists of lateral stretching and twisting of the spine, toning the internal organs and reaching new horizons while tranquilizing the mind. These are, Ardha Matsyendrasana and Jathara Parivartanasana.

Back Bending Asanas:
These bring physical and mental sharpness and alertness. The postures are the opposite of forward bends as are the effects. In forward bends the posterior spine is extended, bringing consistency and mental peace, whereas in back bends the anterior spine is extended and stretched. The effect is invigorating and enlivening. Such asanas are, Ustrasana, Bhujangasana and Matsyasana.

Balancing Asanas:
These strengthen the arms and wrists and exercise the abdominal organs. They also make the body feel light and help attain a good bearing. Salamba Sirsasana, Niralamba Sarvangasana and Salamba Sarvangasana are some of the balancing asanas.