Jor-El was a scientist on the planet Krypton. He and his wife, Nimda An-Dor, had three sons: Jor-El II and Nim-El, who were identical twins, and a younger son, Zor-El.
Jor-El created an experimental rocket ship that could travel through hyper-space. He journey in the ship to the Sol system, where he discovered Earth. On his return to Krypton he kept extensive notes about Earth that he passed down to his eldest son, Jor-El II. Jor-El II later used this information to enable him to save his son, Kal-El, from the destruction of Krypton.