Isaac was the son of promise to Abraham and Sarah, and the half-brother of Ishmael (who became the father of the Arab people) and the father of Esau (from whom came the Edomites) and Jacob. Isaac was born of a mother beyond childbearing age by a miracle of Yahweh, and was a focus of the testing of Abraham and Sarah, his parents.
The name Isaac means "to laugh, or he laughs," which is based on the response of Sarah to Yahweh's statement to Abraham that she was to bear a son. Sarah was hiding out of sight when this announcement was made by the Angel of Yahweh, and upon hearing this statement, she laughed, which she denied later before the angel. Such an idea was considered impossible but happened as promised by the heavenly visitor. Later, Abraham's faith was tested when God commanded him to sacrifice his only son, Isaac. He followed through with this command of God but received him back alive, since Yahweh kept him from doing so, declaring that now He knew by experience (see the meaning of Hebrew yada') that Abraham did not withhold his son.
Later in Isaac's life, he married Rebekah, who bore him Jacob (biography) and Esau (his favorite), and was tricked by Jacob and Rebekah into giving his younger son Jacob his blessing.
See also Biographies of Bible Characters, People and Characters in the Bible.