Short answers, pulled from the story.
The Rings of Power are magical artefacts in J. R. R. Tolkien's legendarium, most prominently featured in The Lord of the Rings. Twenty Great Rings were forged by the Elven-smiths of Eregion under the secret guidance of the dark lord Sauron, who then forged the One Ring in the fires of Mount Doom to control all the others. Many lesser rings with minor powers were also made during the same period.
The Elven-smith Celebrimbor, grandson of Fëanor, led the forging of the Great Rings in Eregion, guided by Sauron disguised as Annatar, the Lord of Gifts. Sauron then secretly forged the One Ring in Mount Doom, investing almost all of his own power into it, to govern and control all the other Rings.
The Three Elven Rings are Narya (the Ring of Fire, set with a ruby), Nenya (the Ring of Water, made of mithril and set with a white stone), and Vilya (the Ring of Air, made of gold and set with a sapphire). Their final bearers were Gandalf, who received Narya from Círdan at the Grey Havens; Galadriel, who bore Nenya and used it to preserve Lothlórien; and Elrond, who inherited Vilya from Gil-galad and used it to safeguard Rivendell.
Four of the Seven Dwarf Rings were consumed by dragons, and Sauron eventually recovered three of the remaining ones. The last of those three was seized from Thráin II during his captivity in Dol Guldur. Before the War of the Ring, Sauron's envoy offered Dain II Ironfoot those rings plus the lost realm of Moria in exchange for help locating the One Ring, but Dain refused.
The Nine Rings were given to leaders of Men who were kings, sorcerers, and warriors. Over time, all nine were corrupted by the power of the One Ring, their lifespans unnaturally extended until they faded into permanent invisibility. By the end of the Second Age, all nine had become the Nazgûl, the Ringwraiths, Sauron's most terrible servants.
Tom Shippey, a Tolkien scholar, identified Tolkien's work on a Latin inscription at the temple of Nodens at Lydney Park as a "pivotal" influence; the site combined a cursed ring, a god-hero linked to Nuada of the Silver-Hand, and a location called Dwarf's Hill. Germanic legend, including Andvaranaut and Richard Wagner's Der Ring des Nibelungen, also contributed to the concept.