In practice Iyengar yoga focuses particularly on three aspects. Correct body alignment allows the body to develop harmoniously in an anatomically correct way so that the student suffers no injury or pain when practicing correctly. As all bodies are different and people have different weaknesses and strengths. Mr Iyengar has also developed the use of props to help the body into the correct positions required. Props are objects like bolsters, blocks, chairs, blankets and belts that help one adjust or support oneself in the different postures so that one can work in a range of motion that is safe and effective.