In Tantra Yoga, the subtle bodies of energy and spirit are developed to create a bridge from the physical to the Devine. The development of energy is focused on the purification and cultivation of prana and the activation of kundalini. The physical body is used to activate energy through the practices of asana, pranayama, mudra, and shatkarma. Thus, the Tantra yogis developed the yoga postures (asana) and breathing exercises (pranayama) that are most commonly used today in Hatha Yoga. Mudras include hand gestures and an intense fusion of asana, pranayama, and bandha. Shatkarma (often referred to as kriya) are esoteric exercises and techniques to purify the body and cleanse the energy pathways. The devotional practices of mantra, yantra, and puja are used to develop the spiritual body.