Approach Įach asana is named in Sanskrit with its etymology, graded, and described separately with two or more pages of text and monochrome photographs of Iyengar.

The book has a glossary of all the Sanskrit terms employed. A second appendix defines the asanas supposed to be 'curative' for a range of diseases and conditions from 'Acidity' to 'Varicose Veins'. which postures to do each week, building up in difficulty, in courses structured to last up to 300 weeks. An appendix defines a set of asana courses, i.e. The book has three parts: a technical introduction to yoga, in which hatha yoga is explained to be one of the eight limbs of yoga a detailed illustrated description of the asanas (some 200 postures, illustrated by some 600 monochrome photographs of Iyengar), followed by a brief account of the bandhas and kriyas and an account of pranayama, yoga breathing. A yoga brick, another of Iyengar's innovations, is helping to ensure correct alignment. Utthita Trikonasana, the extended triangle pose, an innovation basic to Iyengar Yoga. The book became an international best-seller it has been translated into at least 23 languages including Chinese, Czech, Hebrew, Japanese, Hungarian, Portuguese, Russian, and Thai and has sold over three million copies. A paperback edition was published by The Aquarian Press in 1991 under the Thorsons imprint. Light on Yoga was first published in English by George Allen and Unwin in 1966, with a foreword by his pupil, the violinist Yehudi Menuhin. Iyengar made yoga popular, first in India and then around the world. The violinist Yehudi Menuhin became his pupil in 1952 and then invited him to teach in Europe, which he did from the 1960s.

At the age of 18 he decided to spend his life doing yoga, and by 1938 he was already performing the asanas fluently. In childhood he suffered from diseases including typhoid, malaria and tuberculosis, and became extremely stiff. Iyengar (1918-2014) was born in a poor family of Brahmins in Karnataka, India. In the Western world, however, yoga is often taken to mean a modern form of medieval Hatha yoga, practised mainly for exercise, consisting largely of the postures called asanas. Yoga is a group of physical, mental, and spiritual practices from ancient India, forming one of the six orthodox schools of Hindu philosophical traditions. The violinist Yehudi Menuhin invited Iyengar to teach in Europe.

Light on yoga