Why is the figure 8 on a bight knot used?

The figure 8 on a bight knot is commonly used to secure a loop for belaying because it creates a strong and reliable loop in the middle of a rope without needing the ends of the rope. This knot is particularly advantageous in climbing and rescue situations where a loop is required for attaching the rope to a harness or an anchor. The knot’s structure allows it to maintain strength and stability under load, making it ideal for use in scenarios where a belay loop is necessary.

When belaying, this secure loop can facilitate a controlled descent or ascent of individuals, ensuring that the climber or rescuer is safely attached to the rope system. The figure 8 on a bight is also easy to untie after being loaded, which is a critical feature in the context of rescue and climbing.