The Elves (or Eldar) called themselves the Quendi and were the first and eldest of the Children of Eru in the Lord of the Rings Universe.
Elves, like Men, are the children of Eru; however, they are effectively immortal, in that their bodies do not age. They can be killed by physical injury however, or they may come to death from wasting away if after long eons of life they lose the will to live.
They have far better vision and hearing than Men. They also have skills and abilities beyond what is possible for Men and are light of foot and can travel long distances without leaving tracks. They are expert archers and skilled warriors and have spent eons together with Men fighting the oppression of the Dark Lords.