In yoga, asana refers both to the place in which a practitioner (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 ashtanga yoga.