Isaacs wife Rebecca (Rivka) gave birth to fraternal twin sons: Jacob (Ya'akov) and Esau. The two brothers were at war with each other even before they were born. They struggled within Rebecca's womb. Esau was Isaac's favorite, because he was a good hunter, but the more spiritually-minded Jacob was Rebecca's favorite.
Esau had little regard for the spiritual heritage of his forefathers, and sold his birthright of spiritual leadership to Jacob for a bowl of lentil stew. When Isaac was growing old, Rebecca tricked him into giving Jacob a blessing meant for Esau. Esau was angry about this, and about the birthright, so Jacob fled to live with his uncle, where he met his beloved Rachel. Jacob was deceived into marrying Rachel's older sister, Leah, but later married Rachel as well, and Rachel and Leah's maidservants, Bilhah and Zilphah. Between these four women, Jacob fathered 12 sons and one daughter.
After many years living with and working for his uncle/father-in-law, Jacob returned to his homeland and sought reconciliation with his brother Esau. He prayed to G-d and gave his brother gifts. The night before he went to meet his brother, he sent his wives, sons, and things across the river, and was alone with G-d. That night, he wrestled with a man until the break of day. As the dawn broke, Jacob demanded a blessing from the man, and the "man" revealed himself as an angel. He blessed Jacob and gave him the name "Israel" (Yisrael), meaning "the one who wrestled with G-d" or "the Champion of G-d." The Jewish people are generally referred to as the Children of Israel, signifying our descent from Jacob. The next day, Jacob met Esau and was welcomed by him.
Jacob fathered 12 sons: Reuben, Simeon, Levi, Judah, Zebulun, Issachar, Dan, Gad, Asher, Naphtali, Joseph and Benjamin. They are the ancestors of the tribes of Israel, and the ones for whom the tribes are named. Joseph is the father of two tribes: Manasseh and Ephraim.
Joseph's older brothers were jealous of him, because he was the favorite of their father, and because he had visions that he would lead them all. They sold Joseph into slavery and convinced their father that Joseph was dead. Joseph was brought into Egypt, where his ability to interpret visions earned him a place in the Pharaoh's court, paving the way for his family's later settlement in Egypt.
Sources: Judaism 101