Haṭha Yoga is based on the basic principle of yoga as union. It is the union of the two polarities that we find universally throughout the nature. Haṭha Yoga represents this duality in human body as ‘Ha’ which is piṅgalā or right nostril and ‘Ṭha’ which is iḍā or left nostril. There are several representations of piṅgalā (right nostril) and iḍā (left nostril), the most relevant from the yoga practice.