The fictional ring at the center of J.R.R. Tolkien’s The Lord of the Rings is the One Ring. Sauron forged it in the fires of Mount Doom to control the other Rings of Power and extend his influence over their bearers.
The One Ring is made of gold and bears an inscription in the Black Speech of Mordor, visible when heated. Its power is tied to Sauron because he placed much of his own strength into it. Destroying it in the same volcanic fire where it was made is the central condition for defeating Sauron.
The One Ring should not be confused with the other named rings, such as Narya, Nenya, and Vilya, which were associated with the Elves. Nor is it the Ring of Barahir, an heirloom with a separate history. Tolkien’s title refers to the wider conflict surrounding this single dominant ring.