Isaac was the son of Abraham and Sarah. When Abraham was 100 years old and Sarah was 90, three angels came up to Abraham and told him that in one year they would have a son. Abraham bowed to G-d, but Sarah just laughed. That is the reason why they named him Isaac, meaning laughter.
The most famous story about Isaac is his near-sacrifice. When Isaac was young, G-d told Abraham to sacrifice him. Although Abraham was upset he took Isaac and set out to Mount Moriah. When Abraham put Isaac on the altar, an angel told him to stop. G-d provided a ram for them to sacrifice instead.
After Sarah died, Abraham sent his servant, Eliezer,to find a wife for Isaac from among his family. Rebecca agreed to return with Eliezer to marry Isaac. Rebecca and Isaac had twin sons Esau, born first, and Jacob.
When Isaac got older he became blind. He wanted to give a first-born blessing to Esau but Jacob tricked him Jacob put animal hair on his skin so that his father would believe he was Esau. Isaac felt the hairy skin and fell for the deception. Isaac ended up blessing Jacob even though Esau was the first born.
The Hebrew spelling of Isaac's name is יִצְחָק.
Wikipedia's article on Isaac