Bowline

The king of knots. A fixed loop that won't slip, won't jam, and unties even after a heavy load.

What it is

The bowline makes a fixed loop at the end of a rope. It won't slip under load, won't jam after a heavy pull, and unties with a flick of the wrist — even wet, even frozen.

How to tie it

1.  form a small loop (the "rabbit hole") in the standing part
2.  pass the working end up through the hole
3.  around the standing part
4.  back down through the hole
5.  dress and set — the loop stays fixed

When to use it

Mooring a line, rescuing (the "lifeline" knot), tying a halyard, or any time you need a loop that holds and releases cleanly. It's the first knot every sailor learns.