The bowline knot  is an ancient and simple knot used to form a fixed loop at the end of a rope. It has the virtues of being both easy to tie and untie; most notably, it is easy to untie after being subjected to a load. The bowline is sometimes referred as King of the Knots because of its importance. It is one of the four basic maritime knots (the other three are figure-eight knot, reef knot, and clove hitch.  The bowline is often considered one of the most essential knots.