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). The style often makes use of props, such as belts, blocks, and blankets, as aids in performing the asanas. The props enable beginning students, the elderly, or those with physical limitations to perform the asanas correctly, minimising the risk of injury or strain.