Bilbo Baggins finds the One Ring in Gollum’s cave in J.R.R. Tolkien’s The Hobbit.
After becoming separated from the dwarves beneath the Misty Mountains, Bilbo discovers a golden ring on the ground. He later encounters Gollum, who challenges him to a riddle contest. The ring’s power to make its wearer invisible helps Bilbo escape from the underground tunnels.
In The Hobbit, the ring initially appears to be a useful magical object. Tolkien later revised the novel and connected the ring more explicitly to the central history of The Lord of the Rings. It is the master Ring created by Sauron to control the other Rings of Power and preserve his influence.
The One Ring is not the same object as Sting, Bilbo’s sword, or the Arkenstone, the jewel sought by Thorin Oakenshield. Bilbo later gives the ring to Frodo, whose quest is to carry it to Mount Doom and destroy it.