Figure 8 (knot)
A figure 8 knot is commonly used in live-load rope work. It is similar to a simple overhand, but with one additional half twist. This extra half twist substantially reduces the loss of rope strength due to the knot, which is why the figure 8 is usually preferred to the simpler overhand when rigging systems for human weight.
Retraced (rethreaded, follow-through)
This variation is most commonly used to tie the end of a rope around a closed loop, such as in a climbing harness, or a fixed anchor like a tree branch. If a different rope is used to retrace the initial knot rather than the end of the same rope, this variation can be used to join two ropes (Animated knots: Figure 8 (join))
On a bight
The variation is most commonly used to create a strong loop in the end of a rope.
This variation is most commonly used to create a haul or attachment point in the middle of a rope.