A bad explanation of Tolkien mythology and backstory of Rings of Power
In the beginning, Eru (the Creator) created the Ainur. The Music of the Ainur created Eä (the Universe) and Arda (the World). The Ainur who entered that Creation as its guardians are known as Valar (greater Ainur) and Maiar (lesser Ainur).
In a sense, Ainur are angels. Valar are the upper choir and Maiar are the lower choir. *
Many of the Ainur who entered Creation have names. Among them is Vala Melkor, the bad boy of the group, who was cast out and retreated to Arda. He continued to misbehave on Arda, stealing three Silmarilli and destroying the Two Trees for good measure. The Elves didn’t like this, and gave him a new name: Morgoth.
The Dwarves mention Aulë on occasion. Vala Aulë’s domain is smithing/metalworking. (Get it??) One of Vala Aulë’s associates was Maia Mairon. Maia Mairon shifted allegiances to Vala Melkor, and eventually became known as Sauron.
Sauron, a skilled metalworker (previously under Aulë), approached Celebrimbor about making special rings, while Sauron planned to make one for himself.
And that’s what happened just before Rings of Power.
* The Valar eventually sent a group of Maiar to Arda to deal with Sauron’s shenanigans. They are known as Istari (or wizards!)
p.s. Tap the #ainur tag to see an updated version