What type of knot is also known as a stopper knot?

The figure 8 knot is commonly referred to as a stopper knot. Its primary function is to prevent the end of a rope from unraveling or slipping through a fitting or a block. The structure of the figure 8 knot creates a large, bulky knot that effectively stops movement, which is why it's frequently used in climbing and sailing.

This knot's design provides a stable, secure form that is easy to tie and untie, which is essential in various marine applications. It also retains about 75% of the rope's strength, making it a reliable choice when securing lines and preventing slippage.

While the other knots have specific uses, such as the bowline knot for creating fixed loops, the clove hitch for securing lines to posts, and the sheet bend for joining two ropes of different sizes, none fulfill the primary role of a stopper in the way that the figure 8 knot does.