In J. R. R. Tolkien's legendarium, an Elf is an individual member of one of the races that inhabit the lands of Arda. Elves first appear in The Hobbit and remain prominent in The Lord of the Rings, but their complex history is described in full only in The Silmarillion, edited and published after Tolkien's death. More details about them are given in the author's other writings edited and published since then, such as Unfinished Tales and The History of Middle-earth.

Elves are sometimes called the Firstborn or the Elder Kindred (as opposed to Men, the second born) as they were "awakened" before Men by the creator of the universe, Eru Ilúvatar. The Elves named themselves Quendi ("the Speakers"), in honour of the fact that, when they were created, they were the only living beings able to speak.

More informations will come soon. In the meantime, you can visit Wikipedia for more details about Elves. :)