*00:20 I say square knot - but I mean half knot. Apologies!
A knot in it's own right
Half knot is one half of the square knot. I believe that’s why it’s called a "half" knot. Half knot can be used on its own to make very pretty surfaces, even if on its own the knot does not hold very well at all. This knot is sometimes also referred to as the spiral half knot, since it creates lovely spiraling braids if repeated many times in a row.
Step by step instructions
You’ll need four strands of cord, attached to a dowel or a filler cord. The two inner most cords are your filler cords, and the two outer most cord are the knotting aka working cords. We'll number these cords from 1 to 4 starting from left.
The knot can be made either by having the left cord (number 1) or right cord (number 4) in the front. Here are the instructions on how to make it with the left cord in front. See the video for both ways.
Bring cord number 1 over the two central filler cords. Then bring cord 4 over cord 1.
Take cord 4 to the back of the filler cords (2 and 3) and bring it back to front through the loop that the filler cords created with cord 1.
This is a half knot.
If you repeat many half knots in a row this creates a spiraling braid, which looks like DNA.