In the practice of Yoga, Asana denotes the art of sitting still and also any posture useful for restoring and maintaining a practitioner's well-being and improving the body's flexibility and vitality, cultivating the ability to remain in seated meditation for extended periods. Such asanas are known in English as "yoga postures" or "yoga positions". Any way that we may sit or stand is an asana while a posture used in yoga is called a yogasana. Modern usage includes lying on the back, standing on the head and a variety of other positions.
In yoga, asana refers both to the place in which a practitioner (yogin or yogi if male, yogini if female) sits and the posture in which he or she sits. In the Yoga Sutras, Patanjali defines asana as "to be seated in a position that is firm, but relaxed". Patanjali mentions the ability to sit for extended periods as one of the eight limbs of his system, known as Raja yoga, but does not mention standing postures. Beginners generally find it surprisingly difficult to sit still for the one hour (as practised in meditation methods such as Vipassana).
Yoga in the West is commonly practised in physical exercise or alternative medicine rather than as a basic meditation skill.