Another prop which is one of the most popular props which was introduced by BKS Iyengar is Brick/block. A yoga block can be used as an extension of the hand, or to support the back, hip, head, feet etc. One can use a fat book instead of a block if they don't have a brick. Brick is an innovative prop which is excellent for beginners.
The block shortens the distance between the hand and the supporting surface (in a sense, it lifts up the floor to meet your hand), making it easier to lift your torso, expand through the chest and keep your upper body in alignment without collapsing into the side body.
Its an excellent way to introduce beginners to yoga as blocks make all poses more accessible.It also help advanced practitioners advance into, postures that would otherwise be inaccessible. When your body is attempting to enter a new pose that’s (currently) past its limits, your muscles tense up (in the wrong ways – not in the muscle-building ways), actually keeping you from going deeper into the pose. A block gives the necessary support and ease into the pose and by default improve you asana practice.