The hangman's knot works on the same principle as the Scaffold knot. It's a self-tightening loop that provides a high degree of security.
It's easy to make, very strong and allows you to attach a lure or hook to your leader.
For greater visibility, I've made this tutorial with 40/100 fluorescent thread.
Here's how to do it:
Step 1
Pass your line through the eye of your hook.

Step 2
Tuck the free end and the main end between your fingers to create a loop. Point the free end towards the hook without crossing the main line.

Step 3
Make a turn around your loop, then pass the free strand back through the resulting loop. Your thread will now trap the first loop.

Step 4
Repeat this operation 3, 4, 5 times, depending on the diameter of your wire, making sure to work your way up to the reel.

Step 5
Moisten your knot and start tightening it gradually.

Step 6
Gradually slide your knot against the eye of your hook and finish tightening.
All that's left to do is trim off the excess and your knot is complete.

Benefits
- Solid.
- Easy to make.
- Very secure, as it tightens more and more with tension.
The number of turns can be varied according to the diameter of your wire.
Disadvantage
- Difficult to achieve with large-diameter fluorocarbons due to their lack of flexibility.