The Third Age, often abbreviated to T.A., began after the first downfall of Sauron, when he was defeated by the Last Alliance of Elves and Men following the downfall of Númenor.

This age was characterized by the rise and decline of the exiled Númenorean kingdoms, in contrast to the slow recovery of Sauron's power. In the meantime the Elves, Dwarves and other peoples did little new; also known as the Fading Years, the Age marked the waning of the Elves.

It lasted for 3021 years, only ending after the defeat of Sauron had finally and utterly been achieved by destroying his Ruling Ring. With the One Ring gone, the power of three rings waned and the realms that had been preserved by them began to fade. These events prompted many of the Eldar remaining in Middle-earth to sail for the Uttermost West, and so much memory and beauty were lost to Middle-earth forever. After the Last Riding of the Keepers of the Rings, the Fourth Age began.