What is the name of the ring forged by Sauron in J.R.R. Tolkien's legendarium?

The ring forged by Sauron in J.R.R. Tolkien's legendarium is the One Ring.

Sauron created the One Ring in the fires of Mount Doom during the Second Age. He invested much of his power in it so that it could dominate the other Rings of Power and help him control their bearers. Its inscription is written in the Black Speech of Mordor.

The One Ring is central to The Lord of the Rings because Sauron's power cannot be permanently defeated while the Ring survives. Frodo Baggins carries it to Mount Doom, where the creature Gollum accidentally causes it to fall into the fire.

The One Ring is not the same as Narya, Nenya, or Vilya, which are the three Elven Rings. The Ring of Barahir is an older heirloom of the House of Bëor and has no connection to Sauron's ring-making project.