Traditionally promise rings or couple's rings referred to a promise of love made between a couple. But today there are different types of promises of love which people want an outward symbol for. The rings for these different types of promises are often collectively referred to as promise rings. Because of this, it is necessary to provide the different types or categories as a part of this definition.
The promise rings of today may be broken down into three major categories: pre-engagement rings, friendship rings and abstinence rings (also called chastity or purity rings). Each has its own significance and needs defining.
Pre-engagement rings are the traditional promise rings. These rings represent a promise of exclusivity and at least serious intentions for an engagement at a later date. This engagement could be postponed due to the age of the couple for a couple in high school or college, for financial reasons for couples who want but cannot afford a wedding or to allow a period of "real" time and exclusivity to allow the couple to get to know each other on a deeper level and decide if they really want to marry. The latter is very much an engagement but the giving of promise rings allows for a "pre-engagement" without the large outlay of cash that many spend on engagement rings.
Friendship rings are given to show love, appreciation and a commitment to remain friends long term. These rings are given to a best friend or best friends. But the friendship rings could also be given as an exchange of matching promise rings between best friends. Though these rings could be given at any point during the friendship, giving the friendship rings after the friendship has been tested and shown to be true and not merely a close association gives these promise rings more meaning.
Abstinence rings, like friendship rings, are not symbolic of romantic love but are outward symbols of a promise to remain abstinent or chaste until marriage. Today, however, abstinence rings (also called chastity or purity rings) may also be used to symbolize a promise to remain drug free. This promise may be a religious commitment to God, to self, to the wearer's future, to the future spouse and/or to parents. Purity or Abstinence rings may represent a commitment to several people.
In summary, promise rings are symbolic of romantic love that goes beyond the sparks that fly when you see someone attractive, the love of a friend that goes beyond just enjoying hanging out together as friendship rings and a self love or obedient love that is willing to sacrifice to an extent the pleasures of the present for the hopes of the future as abstinence rings. Promise rings symbolize a commitment to love in a deeper more meaningful way.