What is the origin of the idiom "tie the knot" and when to use it?

The exact origin of the phrase "tie the knot" is uncertain but it is believed to have originated from the imagery of tying a knot to represent the joining together of two individuals in marriage. Metaphorically, the act of tying a knot is often associated with making a secure and unbreakable bond or commitment. This notion is applied to the context of marriage, symbolizing the union and lifelong commitment between two people. This phrase is commonly used to refer to the act of marriage.