“At that time, Sauron was still able to appear fair of face and form and he used treachery and deceit as his main weapons. He went among the Elves and Men, wearing a fair form, and bearing fair names, including Annatar. Many of these showed reverence to Aulë. Gil-Galad refused all dealings with him, but not so the Elves – Celebrimbor of Eregion made a pact with Sauron and together they began to forge the Rings of Power.”

Quoted from the CoE Encyclopedia listing for “Sauron”, written by hungry123hobbit.