Earth is the home planet of Humans(and some human/alien hybrids) and many animal life forms,located on the Solar System. It appears as the common setting in many Ben 10 episodes. An odd thing about the planet is that a great deal of alien activity happens on earth which isn't a trans-galactic level civilization. This has led to the majority of the plot lines within the Ben 10 series, as well as a major story arc within Ben 10: Alien Force. Earth, as well as a number a planets, is regarded as a "Cesspool" of the galaxy by one of the bounty hunters, Vulkanus, within the episode The Galactic Enforcers.
It is the main setting of the game where the Potis Altiare was sent by the galvan when it crashed on earth many years ago.
The Earth begins to have a substantial ethnicity diverse population of aliens sometime between Ben being 15 and 30. When exactly isn't disclosed and may well be non-cannon due to the events of Ben 10: Alien Force.
Another alternate future of the Earth was seen in Paradox, when Professor Paradox showed Ben and the gang what will happen if the time-warping creature gets out of Los Soledad and wanders off in the whole world with the Earth looking like a deserted wasteland.