List of asanas
An asana is a posture, whether for traditional hatha yoga or for modern yoga; the term is derived from the Sanskrit word for 'seat'. While many of the oldest mentioned asanas are indeed seated postures for meditation, asanas may be standing, seated, arm-balances, twists, inversions, forward bends, backbends, or reclining in prone or supine positions. The asanas have been given a variety of English names by competing schools of yoga. The traditional number of asanas is the symbolic 84, but different texts identify different selections, sometimes listing their names without describing them. Some names have been  given to different asanas over the centuries, and some asanas have been known by a variety of names, making tracing and the assignment of dates difficult. For example, the name Muktasana is now given to a variant of Siddhasana with one foot in front of the other, but has also been used for Siddhasana and other cross-legged meditation poses. As another example, the headstand is now known by the 20th century name Shirshasana, but an older name for the pose is Kapalasana. Sometimes, the names have the same meaning, as with Bidalasana and Marjariasana, both meaning Cat Pose. Affixes . Variations on the basic asanas are indicated by Sanskrit affixes including the following: Asanas. A single asana is listed for each main pose, whether or not there are variations. Thus for Sirsasana (Yoga headstand), only one pose is illustrated, although the pose can be varied by moving the legs apart sideways or front-and-back, by lowering one leg to the floor, by folding the legs into lotus posture, by turning the hips to one side, by placing the hands differently on the ground, and so on. Iyengar's 1966 "Light on Yoga" lists 15 variations on the basic headstand , including for instance the combined variation Parivrttaikapada Sirsasana in which not only are the hips revolved but the legs are apart front-and-back. Since then, variations of many other poses have been created; their names are not listed here. Yin Yoga names are for the equivalent Yin variants; these are usually somewhat different from the conventional (Yang) poses. Indian texts are "notoriously difficult to date". The table shows the approximate date and abbreviated title of the earliest document or authority to describe that asana (not only naming it), as follows: