The surgeon's knot is a modified version of the reef knot. When tying the first throw, it adds an extra twist, which forms a double overhand knot.
The extra turn helps reduce loosening by providing more friction while the second half of the knot is tied. It is quite commonly used by surgeons
because the importance of maintaining tension on a suture, and hence its name. It is also one of the best and easiest knots for joining lines of
any diameter and approaches 100% line strength when tied properly.