A yoga block is a rectangular shaped block tycially made from a dense foam. It is used as a prop in yoga asana practice. The purpose of a yoga block is to help stabilize poses and make them more accessible to yogis of different abilities and body types. In addition, yoga blocks can be used to deepen a pose or stretch. They are particularly useful for adding stability to balancing asanas such as crescent moon pose, supported back bends such as bridge pose and many more.