Literally, the "Lonely Isle," Tol Eressëa was home to myriad groups of Elves, mainly the Teleri. The isle was used to ferry the Elves from Middle-earth to Aman by Ulmo and Ossë when the Elves were summoned by the Valar to come to Valinor after their awakening in Cuiviénen. The Teleri, the last group to be taken to Aman, begged Ulmo to stop their voyage. Ulmo did so, leaving the isle set in the Bay of Eldamar off Aman's coast. There the Teleri, mariners by heart, lived for many years within sight of the light of Valinor which flowed through the Calacirya. After living there for quite a long time, they desired to live fully in the light of Valinor and to be reunited with their Elven kin who had gone to Valinor long before. Eventually, the Teleri built ships with the help of Ossë and came at last to the shores of Aman where they dwelt in Alqualondë on the Bay of Eldamar.
Tol Eressëa sat deserted until the end of the First Age, when the refugee Elves of the Sinking of Beleriand made their home there in reconciliation with the Valar. Tol Eressëa was impossible for all but the Elves to find, as it was protected by the Enchanted Isles, and later sundered along with Aman from Middle-earth, but the tower of Avallónë upon Eressëa could still be seen by those Númenóreans with sharp eyes from the Meneltarma, or later after the destruction of Númenor it could be seen with the Palantir of Elendil that sat in the towers of Emyn Beraid.
Reference - The Silmarillion
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