Earth is the planet that housed humans before operation cleanup.
Earth is the place that the Earthlings polluted making the Earthlings leave to the axiom ships, leaving WALL-Es to clean up the mess. After a while, all WALL-Es are destroyed except for one.
Before 2105[]
As Buy N Large continued to grow and dominate all industries, they start running out of space to dispose of rubbish.
2105[]
The human population reaches 200 Billion, and there are no places to dispose of rubbish. Buy N Large begins Mission Recolonise, sending starliners out into space (most notable being the Axiom), and leaving WALL-E Units, and incinerator units on the Earth performing operation cleanup.