How to make a plain knot
The "plain or square knot" is derived from marine use, since it is used to join two ends of a rope when a sail is curled. It is one of the most famous maritime knots outside the nautical scope. The result is a double loop knot, often used to tie shoelaces. The "loop knot, plain or square" , does not constitute a very secure joint, so it should not be used, of course, with different diameter ropes..