Elrond has a daughter, Arwen, who famously marries Aragorn after his corronation to the throne of Gondor. He also has a twin brother, Elros. Elros chose to be human, thus giving Elrond the right to be Elvish, and have immortality. Elrond also fathered twins, Elrohir, and Elledan. Elrond's wife was killed by orcs in the early Third Age.
At the start of the Second Age, Elrond and Elros were each given the choice if they wanted to be counted as man or elf. Elros chose to be counted as man, and was made the first King of Númenor. Therefore, Elrond chose to be elf, and served as Gil-Galad's captain in the Kingdom of Ñoldor. In the middle Second Age Elrond housed the first White Council at Rivendell, where it was decided he should remain as Lord of Rivendell.
At the end of the Second Age Elrond rode beside Gil-Galad to the Black Gate with the Last Alliance of Elves and Men at their backs. Only three commanders of the alliance survived, Elrond, Cirdan, and Isildur. Upon victory, Isildur took the One Ring from Sauron and kept it as a token for the loss of life of his brother and father. Elrond urged him to destroy him, knowning it would poison his mind, but Isildur refused. Elrong returned home to Rivendell upon the victory at the Black Gate.
Elrond's wife was attacked by orcs in the early Third Age. When it was evident she was not going to be able to recover from her wounds she sailed to the Undying Lands. Elrond decided stay, knowning their was still evil at work in Middle Earth. Also he was a member of the White Council, and they urged him of his duties still in Middle Earth.
In the years following Isildur's death, Elrond would house the heirs as long as the line lasted, the most famous of them being Aragorn. After Aragorn's father was slain in battle Elrond brought him to Imladris to be raised. When Aragorn reached manhood Elrond told him of his kingly lineage.