During the party Bilbo announces his departure and disappears with the use of the magical ring that makes its wearer invisible and his discovery of the ring is chronicled in The Hobbit. Before leaving the Shire, however, he returns home. Although he intends to give all his possessions to his young relative and heir which is Frodo, at the last minute he balks at leaving behind the ring. However, he is persuaded to do so by the wizard Gandalf, who later learns that Frodo’s ring is the One Ring, the most powerful of the 20 Rings of Power. It was fashioned by Sauron, the Dark Lord of Mordor, to rule the other rings and enable him to conquer and enslave the world.
Gandalf tells Frodo to take the ring to the one place where it can be destroyed in the place where it was forged, which is the fires of the Cracks of Doom under Orodruin or also known as the Fire-mountain, in the very heart of Sauron’s realm of Mordor.
Sauron becomes aware that has been found yet again, he raises his Orc armies preparing for a new takeover of the ring
Until it has been discovered by Smeagol and being obsessed with the ring and become Gollum then during the journey of Bilbo he spills the ring until he gets home bringing the ring
It's beginning Sauron were in who delivers twenty rings of power to the races of middle-earth in order to corrupt them all but he was defeated in battle and his ring was lost in hundred years