see it clearly

Reef Knot

The true "Reef Knot" is merely the square knot with the bight (loop) of the left or right end used instead of the end itself. This enables the knot to be "cast off" more readily than the regular square knot. This knot is so named from being used in tying the reef-points of a sail.

As you can see from the images above and below, the differences are very slight between the true reef knot and the square knot.

How to Tie a Reef Knot

1. Form an overhand knot.
2. Then take the end 'a' over the end 'b' through the bight.
3. If the end were taken under the other end, a granny would be formed.
4. Pull it tight