The Overhand Knot

This is one of the most basic knots. It is the low-tech of knots. It is the building block of many other, more complex knots.

Used by itself, the overhand knot is a stopper: a thicker feature in the rope that prevents it from slipping through a narrow opening, like a hole in an object or even a tight loop in different knot, part of the same or different rope. It is very stable, even becoming jammed, extremely hard to untie. That is clearly very helpful when used for its other common function: to tie up the ends of the rope, preventing them from unraveling.

It is simple enough that probably small kids would discover it without any instructions, by themselves. Also, you might have done it thousand of times already, without paying much attention: have you tied a knot in the neck of a plastic grocery produce bag to prevent the insides from spilling out ? yup.

Here it is, in all its beautiful simplicity:

Pull the ends to tighten it, and it will look something like this, hiding its alternating crossings into a unassuming compact structure:

It has a certain symmetric elegance. When following the rope, for example starting from the right side, enumerating the points where the rope crosses itself has a perfect rhythm: over, under, over, under, over, under. (yes, there are two chiral variants: you could start from the left side going over, under, etc. ). That elegance makes a lot of sense considering the close relationship to a very distinguished relative, almost a twin: the trefoil knot, fundamental to the study of mathematical knot theory, is obtained by simply connecting the ends of the overhand knot.

It is interesting then to notice that an extension, the double overhand knot, which is done by passing once again the end of the rope through the big loop created by the simple overhand knot, adds two crossings, which adds two “over, under” pairs to that list – a nice way to remember.

Can you go triple ? Sure you can: as above, add two more crossings. The “triple” version enhances its properties, an ultimate version of overhand. It becomes even a decorative knot, purportedly worn by monks and nuns.

Then, can you go even further ? Over, under, over, under …