Karana can be defined as the combined movement of arms and legs in a dance. It is not a static pose, it is an action. The "Hatha Yoga Pradipika" states that karanas should be practiced together with khumbakas and asanas in order to reach the goals of Raja yoga. Legend says that Shiva used to dance every evening and his dance consisted of the 108 karanas. The expression of his cosmic dance is called nata yoga.
It is said that out of the 108 karanas outlined in the Natya Shastra, only 36 are usable in the yoga practice and some of the Hatha yoga poses are adaptations of different karanas.