Awakening and Sundering
The Elves were the oldest people created by Eru Ilúvatar. They were awakened in the First Age at the lake Cuiviénen (Quenya: "water of awakening") far in the east of Middle-earth. The Elves were the first creatures to speak and make language, and they called themselves the Quendi, "the Speakers".
The Elves were found by the Vala Oromë, and the Valar invited the Elves to come to Valinor in the West, where they would be safe from Morgoth. What followed is called the Sundering of the Elves. Some of the Elves refused the invitation and stayed at Cuiviénen; they were later known as the Avari ("the Unwilling"), and what became of them is not known. The Elves who accepted the invitation became known as the Eldar, the People of the Stars. The Eldar left Cuiviénen in three groups who became the different Elven tribes: the Vanyar, the Noldor and the Teleri. The Vanyar went first, followed by the Noldor, and arrived in Valinor. The Teleri were the last to journey West. Some of them did not cross the Misty Mountains and stayed behind, and became known as the Nandor. The other Teleri crossed the mountains and continued to Beleriand, where one of their leaders, Elwë, was lost; some of the Eldar stayed behind to search and wait for him. The Teleri finally reached the Sea, and crossed over to Valinor, arriving last of the Elven peoples. The Elves who had remained in Beleriand became known as the Sindar or Grey Elves.
Those of the Elven peoples that arrived in Valinor during the time of the Two Trees were called the Calaquendi (the Elves of the Light), consisting of the Vanyar, Noldor, and the Teleri who had crossed the Sea. Those that did not see the light of the Two Trees of Valinor were known as Moriquendi (the Elves of Darkness). The Sindar are sometimes called Elves of the Twilight, because they have an inbetween status.
- J. R. R. Tolkien, The Silmarillion, Quenta Silmarillion