Iyengar yoga focuses particularly on three aspects. Correct body alignment, that allows the body to develop harmony in an anatomically correct way so that the student suffers no injury or pain when practising correctly.
Iyengar yoga also uses props. The use of these props is comparatively new in the history of yoga and comes directly from Iyengar. The purpose of the props is to assist the student in attaining ideal alignment, even if the body is not yet open enough so wooden blocks, chairs, blankets and belts are used to help one adjust or support oneself in the different postures as all bodies are different and people have difference weakness and strength. This helps to work in a range of motion that is safe and effective.
The other two key aspects of asana practice in the Iyengar system are Correct Sequencing in which there is a powerful cumulative effect achieved by practicing asanas in particular sequences. The concept of Timings means postures are held for considerable lengths of time to let the effects of the poses penetrate deeper within the individual