Yoga is one of the six philosophical schools of thought that defended itself with original Hindu thought. The yoga system helps us to reach the higher level of consciousness through a transformation of the psychic organism. Yoga enables us to get beyond the limit set to ordinary human experience. Yoga sutra of Patanjali is the oldest text available on yoga. Patanjali systematized the conception of the yoga and set them forth on the background of the metaphysics of Samkhya. So these two disciplines were grouped together and called as Samkhya-Yoga. But unlike Samkhya system of thought yoga accept Ishvara as a helpful entity

The six systems, namely Samkhya yoga Nyaya Vaisheshika Mimamsa and Vedanta are together called upangas of Veda. These six systems of thought were in existence for a period much before it was codified. It was very much part of Vedic lore from time immemorial. Dr Radhakrishanan was of the opinion that the six conservative school were compelled to codify their view and set forth logical defense of them because of the onslaught of skepticism prevalent in Buddhism

There are two sources for yoga doctrines, the Patanjali - Astanga yoga and the Tantric - Kundalini Yoga. All the various branches like Rajayoga , Astanga yoga , Hatha yoga , Kriya yoga , Kundalini yoga are derived from these two primary sources of Yoga

Authentic Texts: Patanjali Yoga Sutra, Gheranda Samhita and Hatha Yoga Pradipika