The Phantom Drive is a Kryptonian engine that is capable of accessing black holes by folding space as Kal-El indicated to travel vast distances across the universe almost instantly by passing through the Phantom Zone.
Jor-El built his own Phantom Drive for a small spacecraft designed to carry his newborn son Kal-El away from Krypton's impending destruction. The Phantom Drive was programmed to open a portal to another solar system, namely that of the planet Earth.
After General Zod and his insurgents failed in their attempt to take over Krypton, they were placed in the Phantom Zone. When Krypton exploded, the planet's explosion released their prison ship, the Black Zero, from the Phantom Zone. Adrift in space, Zod and his cohorts retrofitted the Phantom Zone Projector by taking the Phantom Drive and installing it on their ship as a means to travel the universe looking for other surviving Kryptonians.