Bellur Krishnamachar Sundararaja Iyengar was an Indian teacher of yoga and author. He is the founder of the style of yoga as exercise, known as "Iyengar Yoga", and was considered one of the foremost yoga gurus in the world. He was the author of many books on yoga practice and philosophy including Light on Yoga, Light on Pranayama, Light on the Yoga Sutras of Patanjali, and Light on Life. Iyengar was one of the earliest students of Tirumalai Krishnamacharya, who is often referred to as "the father of modern yoga". He has been credited with popularizing yoga, first in India and then around the world.
Iyengar Yoga, named after and developed by B. K. S. Iyengar, and described in his bestselling 1966 book Light on Yoga, is a form of yoga as exercise that has an emphasis on detail, precision and alignment in the performance of yoga postures (asanas).