A little note from the encyclopedia of Arda:
One of the greatest Elves in the history of Middle-earth, Elrond was born at the Havens of Sirion late in the First Age. During their sack, he and his brother Elros were taken captive by the Sons of Fëanor, but Maglor took pity on them and released them. When they were rescued, Elrond was found playing in a cave beneath a waterfall, and so received his name.
Both of Elrond's parents were half-elven, and after the War of Wrath he was given a choice; whether to be counted amongst the kindred of Elves or of Men. He chose the Firstborn, and remained in Lindon with High King Gil-galad.
After the invasion of Eriador by Sauron in the mid-Second Age, Elrond founded a refuge there in a deep hidden valley; this was named Imladris, or Rivendell in the Common Speech. After Sauron's defeat by Tar-Minastir of Númenor, Elrond remained in Rivendell, where he prospered with the aid of the Great Ring, Vilya.
Elrond played a great part in the histories of the Second and Third Ages; he marched with Gil-galad and Elendil to the War of the Last Alliance, and was a leading member of the White Council. At the time of the Council of Elrond in 3018 (Third Age), he had dwelt in Middle-earth for some 6,500 years.
Notes
1 In a letter of 1958, Tolkien gives a very detailed derivation of Elrond. When the Sons of Fëanor attacked the Exiles of Gondolin, Elrond and his brother Elros (both at that time small children) were carried off, but later found near a waterfall; Elrond was discovered in a cave behind the fall - hence 'Elf of the Cave'. However, in a much later letter (1972), Tolkien interprets the name 'Vault of Stars', and Christopher Tolkien gives the similar 'Star-dome' in his Appendix to The Silmarillion. Whether it was Tolkien's intention to change the derivation of Elrond, or whether the older story simply slipped his mind, cannot now be known.
More correctly, Elves don't suffer ageing in the same way as Men. In fact they do age, as Tolkien makes clear in his Letters. There, he says, 'The Elves were sufficiently longeval to be called by Man 'immortal'. But they were not unageing or unwearying' (The Letters of J.R.R. Tolkien No 245, dated 1963).
Yes, yes, yes, he's very good as Elrond! But I still think he is too old: Eldarion does say (by the way thanks for all the cool info) : 'The Elves were sufficiently longeval to be called by Man 'immortal' But they were not unageing or unwearying'.
But Galadriel is so much older than Elrond, and she still looks young.
No One Else Could Play Elrond, He Plays The Part So Well, I Wouldn't Want Any One Else Playing Him. It Just Wouldn't Be The Same, He Is So Hot As Elrond, And The Reason Why I Think He Looks Old , Is because He Has Been Through So Much, and Seen So Much, That It Has Taken A Toll On Him. He Is Also Wise Beyond His Years. I Absolutely Love Him Playing Elrond. 😍