Ring of O refers to a certain style of ring that indicates the wearer is a BDSM practitioner. The name comes from the popular BDSM novel "Story of O" in which the main character wears a ring similar to one that many in the lifestyle wear today.
The ring of O worn by those who practice BDSM today is quite different from the original ring in the novel. In the novel, the ring has a flat, disc-shaped top and is worn by a female slave. The fictional ring bears the symbol for the secret society of Roissy to which the wearer of the ring pledges obedience.
Today the meaning, as well as the style of ring, has changed. Since the 1990s, the ring of O has been made up of a band with a ball that links to a toroidal ring. Individuals that wear the ring choose to do so to indicate that they are interested in BDSM practices.
