Bilbo Baggins finds the One Ring in J.R.R. Tolkien’s The Hobbit.
Bilbo discovers the ring in the Misty Mountains after becoming separated from Thorin’s company. It had been lost by Gollum, who lived beneath the mountains and called it “my precious.” The ring gives its wearer invisibility in ordinary circumstances, although its deeper power and history become much more important in The Lord of the Rings.
In The Hobbit, the ring initially appears to be a useful magical device that helps Bilbo escape danger. Tolkien later revised parts of the book so that its account would fit the darker history revealed in The Lord of the Rings. The artifact is ultimately identified as the master Ring forged by Sauron.
The One Ring should not be confused with the Arkenstone, the treasured jewel sought by Thorin, or Sting, Bilbo’s sword. Those are separate objects with different histories.