Classical Yoga may be defined as yoga that is based on the instructions of the Siva-samhita, Gheranda-samhita, Yoga-Sutra. The word ‘yoga is derived from two roots, one meaning ‘concentration1 and the other meaning ‘union’ that is, the union of the individual self and the Supreme Self. The words are derived from the x same Sanskrit root as the English word ‘yoke’, meaning’to join’. According to Palanjala Yoga-Sutra, yoga is restraining the Citta* or mind, from taking various forms. Here yoga means concentration. But in Raja-yoga, which is traditionally considered a branch of the Tantra-xdstra, yoga means both concentration and union, in the sense of union of the individual self with the Supreme Self. Again, yoga is broadly divided into two parts, Hatha-yoga and Raja-yoga. liatha-yoga, also known as Kriya-yoga, is primarily concerned with keeping the body strong and healthy.