Standing asanas in the context of Mahabalipuram

An āsana (Sanskrit: आसन) is a body posture, originally and still a general term for a sitting meditation pose, and later extended in hatha yoga and modern yoga as exercise, to any type of position, adding reclining, standing, inverted, twisting, and balancing poses. The Yoga Sutras of Patanjali define "asana" as "[a position that] is steady and comfortable". Patanjali mentions the ability to sit for extended periods as one of the eight limbs of his system. Asanas are also called yoga poses or yoga postures in English.

The 10th or 11th century Goraksha Sataka and the 15th century Hatha Yoga Pradipika identify 84 asanas; the 17th century Hatha Ratnavali provides a different list of 84 asanas, describing some of them. In the 20th century, Indian nationalism favoured physical culture in response to colonialism. In that environment, pioneers such as Yogendra, Kuvalayananda, and Krishnamacharya taught a new system of asanas (incorporating systems of exercise as well as traditional hatha yoga). Among Krishnamacharya's pupils were influential Indian yoga teachers including Pattabhi Jois, founder of Ashtanga (vinyasa) yoga, and B.K.S. Iyengar, founder of Iyengar yoga. Together they described hundreds more asanas, revived the popularity of yoga, and brought it to the Western world. Many more asanas have been devised since Iyengar's 1966 Light on Yoga which described some 200 asanas. Hundreds more were illustrated by Dharma Mittra.

Tree pose or Vrikshasana (Sanskrit: वृक्षासन, romanized: vṛkṣāsana) is a balancing asana. It is one of the very few standing poses in medieval hatha yoga, and remains popular in modern yoga as exercise. The pose has been called iconic of modern yoga; it is often featured in yoga magazines, and practised in public displays such as for the International Day of Yoga.

Yoga as exercise is a physical activity consisting mainly of postures, often connected by flowing sequences, sometimes accompanied by breathing exercises, and frequently ending with relaxation lying down or meditation. Yoga in this form has become familiar across the world, especially in the US and Europe. It is derived from medieval Haṭha yoga, which made use of similar postures, but it is generally simply called "yoga". Academic research has given yoga as exercise a variety of names, including modern postural yoga and transnational anglophone yoga.

Postures were not central in any of the older traditions of yoga; posture practice was revived in the 1920s by yoga gurus including Yogendra and Kuvalayananda, who emphasised its health benefits. The flowing sequences of Surya Namaskar (Salute to the Sun) were pioneered by the Rajah of Aundh, Bhawanrao Shrinivasrao Pant Pratinidhi, in the 1920s. It and many standing poses used in gymnastics were incorporated into yoga by the yoga teacher Krishnamacharya in Mysore from the 1930s to the 1950s. Several of his students went on to found influential schools of yoga: Pattabhi Jois created Ashtanga Vinyasa Yoga, which in turn led to Power Yoga; B. K. S. Iyengar created Iyengar Yoga, and defined a modern set of yoga postures in his 1966 book Light on Yoga; and Indra Devi taught yoga as exercise to many celebrities in Hollywood. Other major schools founded in the 20th century include Bikram Yoga and Sivananda Yoga. Yoga as exercise spread across America and Europe, and then the rest of the world.