Yoga, an ancient Indian concept, represents the way of life which endows perfect health comprising physical, mental, ethical and spiritual development. In Sanskrit this word means `to unite`.’ Indeed the practice of yoga leads to the integration of the soul with the Supreme Being. This Hindu discipline is also put into practice to lead a healthy life. In fact, physical education, for the first time, was correlated to health, hygiene, ethics, meditation and even a higher purpose of life by the ancient Yogis of India. Principally, however, yoga does not conceive man only physically. On the contrary it lays greater emphasis on the significance of soul and mind as these characterise man`s personality. The human body is made of a physical body, a mind and a spirit, and the three parts are so dependent on each other that any disturbance in one part affects the whole system. Yoga, thus, has a holistic approach as it regards man as a whole being with body, mind and soul.

History of Yoga
The history of yoga in India can be divided into three eras: Pre-Classical, Classical and Post Classical. Yoga can be easily said to have its origin in Shramanic and Upanishadic traditions. The Pre-Classical age bears testimony to the fact that besides Hinduism, Yoga evolved as a separate identity in Buddhism and Jainism as well. There are several historical sources that trace the existence of yoga to Indus Valley civilisation as well. Seals bearing the image of a figure seating in a yogic pose were excavated from Mohenjo daro. However, written evidences are only found in the Vedas. Probably it is the Rig Veda which, for the first time mentions yoga. Yajur Veda, Atharva Veda and the later Satapath also discuss yoga. Karma Yoga, one of its branches, is to be found in the Lord Krishna`s divine discourse in Bhagavad Gita. However it was in the Classical age yoga was systematically compiled by Maharishi Patanjali for the first time in 5th century BC. He simplified the concepts and principles of yoga so that it could reach out to the masses as well. The traditions of yoga developed further in the Post Classical era. During this period Samhitas, religious works of the Vaishanava sect and others mention this ancient Indian discipline.

Types of Yoga
Yoga can be classified into certain heads. According to Hindu Philosophy, the major branches of yoga include Raja Yoga, Jnana Yoga, Karma Yoga, Bhakti Yoga, Hatha Yoga, Mantra Yoga, Japa Yoga, Purna Yoga, etc. Raja Yoga is also known simply as only "yoga" in the context of Hindu philosophy and was compiled in the Yoga Sutras of Patanjali. It is part of the Samkhya tradition. Many other Hindu texts discuss the various aspects of yoga, including the Bhagavad Gita, Upanishads, the Hatha Yoga Pradipika, the Shiva Samhita and various Tantras. The heritage of yoga was actually handed down from teacher to pupil. Thus, with the passing time new techniques were added to the ones already learned. Thus, several branches of yoga came into existence. Each branch has its separate goal. For instance, Hatha Yoga aims at creating an immortal body that allows mastering nature; on the other hand Raja Yoga aids in discovering the true identity of the self. Different religious beliefs have also contributed in shaping the various kinds of yoga in India.

Yoga Asanas
There are about 84 million postures and these include the pattern of sitting of different species which are known as Asanas. In the beginning the postures which were used for prolonged sitting performing the spiritual practices like Sandhya, meditation, pooja and fire ceremony were known as Asanas. The mythological root of yoga asanas can be traced to Lord Shiva who is said to be seated in the yogic pose (padmasana). As far as written evidences are concerned, asanas had been explained by Patanjali while discussing the Bahiranga Yoga or Ashtanga Yoga for the first time. Yoga insists on the primary need for day-to-day good health. This has to be achieved through physical education which, in turn, promotes moral and mental discipline and psychic absoluteness. Asanas are instrumental in achieving this end. It begins with postural training and rhythmic breathing associated with preventive measures and autotherapy or the process of nerve purification. There are numerous kinds of asanas or poses that can be grouped under Meditative and Cultural poses.

Yoga and Diseases
Yoga has the potential to rejuvenate body-mind complex and reestablish the healthy condition of the practitioner. Through scientific research it has been found that yoga is helpful in controlling several kinds of diseases, such as, hypertension, insomnia, hyperacidity, diabetes, asthma etc. Yoga is also extremely effective in increasing flexibility, since it acts upon the various joints of the body including those joints that are never really on the `radar screen` let alone exercised. It also increases lubrication of the joints, ligaments and tendons. There are different yoga asanas for different systems in the human body as well as diseases. Although the yogic and the modern concepts of the human anatomy differ but the effect of the yogic therapy on its various systems is undeniable.

Benefits of Yoga
Yoga is perhaps the only form of activity which massages all the internal glands and organs of the body in a thorough manner. Yoga acts in a healthy manner on the various body parts. This stimulation and massage of the organs in turn benefits the mass by keeping away diseases. Yoga ensures the optimum blood supply to various parts of the body, by gently stretching muscles and joints as well as massaging the various organs. Regular yoga practice brings about mental clarity and calmness, increases body awareness and also relieves chronic stress patterns, relaxes the mind, centers attention and also sharpens concentration. Yoga strives to increase self-awareness on both physical and psychological level. Studies have also shown that Yoga effects in increased brain activity with better performance and doctors even suggest that yoga can enhance cognitive performance.

Yogic theory and practice in India has been followed since ages. The knowledge attained through Yoga is not merely that of the practical kind relating to techniques, but of a spiritual type pertaining to grasping something about the nature of the self at rest. Yoga is a complete system that includes practices for body, mind and spirit such as ethics, meditation and physical postures. Classical yoga is practical and is applied to daily life. It is total control of personality complexes which reflects after practicing yoga regularly and consciously. Yoga strongly believes in balanced state of mind. In this state, work performed can be of high quality. The science of yoga is for better and healthy living. It is education of total personality development and the most important aspect of Yoga is the sense of confidence that it generates. This is so because the Yogi views whatever is there in the universe, is a miniature form within every being.