In his origin he was a Maia created, as all were, by Iluvatar. He was corrupted by the proud and evil Melkor (Morgoth), and became his lieutenant in the war which followed, against the Elves and Men.
After the fall of Morgoth at the end of the First Age, Sauron fled to Mordor to build his stronghold, Barad-Dur. With his cunning he seduced the Elves and tricked them into forging the Rings Of Power. Three would go to the Elven Lords, Nine to the Lords of Numenor and Seven to the Dwarves.
He then in secret forged the One Ring, the Ruler of all of the others and in it he put much of his power. The Elven smith, Celebrimbor discovered his plans and the Elves retaliated with war. The Elves hid their Three, but the men of Numenor still wore them. With his power in the One, he transformed the men into the Nazgul, horrid immortal servants of Sauron.
The Second Age ended with Isildur, son of Elendil, cutting the One ring from His finger, and destroying the body of Sauron. Yet in the Third age, it became apparent that Sauron had taken refuge in the Great Greenwood, causing a dark shadow to fall upon it and it became known as Mirkwood. There his power grew, and it was now that the five Istari arrived from the West.
Sauron has a special function in Mume. All notorious non-darkie player-killers will be remembered by him.
To check if someone is on Saurons List, type:
tell sauron <name> [For example, "tell sauron ilie"]
While Sauron may comment on those that are not player killers, those that he claims to be his true followers are player killers. Telling him 'list' will provide a list of player killers.
See also: Rules-Sauron