Iyengar Yoga is a school of Yoga that was created by B.K.S. Iyengar. It is very intensive in its poses, hundreds as opposed to the "new fad yoga" aka Bikram which uses only 26 poses. Iyengar wrote a book called "Light on Yoga" which shows all the poses at their fullest, and I mean "fullest" like I mean pictures of B.K.S. bending over backwards to grab his ankles. Fucking unbelievable, but that is how hard he has personally worked. He still teaches to this day in India.