In medieval Europe the belief that knots could prevent the consummation of marriage was widespread.
In some countries, such as the bride and groom, on the day of the wedding, they unbutton the buttons and undo all the knots in their clothes, such as bows, ribbons and laces.
In Spain and in other countries some knots such as the knot plain, can mean the marriage in a couple's marriage forever. Already in itself the word link-to link-means marriage that, as we know, is the union of a couple who acquires this commitment by religious ceremony, civil, etc.
In the case of knots, linking could be joining a rope with another rope or another element by means of a loop knot. In fact, there are different loop knots of the so-called elusive or runners as is the case of the American loop, the double loop, or the same hanging knot.
It is known that Leonardo Da Vinci used to draw knots in some of his works.
In principle the knots can be divided into four large groups: