Hatha yoga is also known as Hatha vidya. This form of yoga was introduced by Yogi Swatmarama, in the 15th century in India. He is also known to be the compiler of the Hatha Yoga Pradipika or book. According to Yogi Swatmarama, Hatha Yoga is a stairway that will finally take you to the new heights of Raja Yoga. As it is considered as a preparatory stage, Hath yoga involves various stages of physical purification achieved through meditation. The word Hatha is made of two words where Ha means the Sun and Tha stands for the moon. Together both of them represent the principal nadis (energy channels) of our body.