Earth is our world in the Skylanders franchise, home to the player Portal Master. After the Core of Light was destroyed, the Skylanders were banished from Skylands and sent to Earth. Upon entering the world's atmosphere, they were turned into toys as a result of Earth having no magic.
Skylanders: Spyro's Adventure
Earth was where the Skylanders were banished to after the Core of Light was destroyed (in the console version of Spyro's Adventure). As a result of Earth bearing no magic, the Skylanders were shrunk and turned into toys. Earth is also the world where the new Portal Master lives.
At the end of the console version of Spyro's Adventure, Kaos was banished to Earth where he was soon tormented by a dog.
It is revealed that the Giants were banished from Skylands to Earth after they defeated the Arkeyans 10,000 years ago. In the present, the Skylanders are still trapped on Earth in toy form; some having been put inside a display in a toy store called Super Toy Planet. Kaos however, broke free of his frozen state due to his status as a Portal Master and used a Portal of Power on a toy display to return to Skylands.
Skylanders: Swap Force
During an epic battle, a brave group of Skylanders were caught in the eruption of a mystical volcano in the Cloudbreak Islands. The result blasted them apart and sent them to Earth. But, the magic of the volcano gave these heroes a remarkable new power -- the ability to swap halves -- turning them into a special team known as the SWAP Force.
Skylanders: Trap Team
The Trap Masters serve as the guards of Cloudcracker Prison to prevent the most notorious villains of Skylands from escaping. However Kaos blew up the prison and sent both the Trap Masters and the Traptanium down to Earth, releasing the villains in order to strengthen his dark army.
With the Sky Eater at his disposal, Kaos was able to sever the Portal network that link Skylands to other worlds including Earth. He announced his victory over Skylands to the player and proceeded to cut them off from the realm, stranding the Skylanders on Earth and leaving the Portal Master without a means to reach Skylands. Luckily, Hugo was able to create a rift into Skylands, allowing the player to transport their Skylanders to fight against Kaos and his newest threat.
Due to an every-20-years occurence, Skylands converges with the Thumpin' Wumpa Islands, which according to Crash Bandicoot lore are a fictional archipelago on Earth. However, the Synchronization Celebration is disturbed when Dr. Neo Cortex and Fake Crash's meddlings disrupt the Vibes of the islands.
Skylanders: Ring of Heroes
Portal Masters from Earth were pulled from their homeworld and into Skylands when Kaos accidentally caused unstable rifts that transported them between dimensions.
- Glumshanks refers to Earth as the Portal Master's homeworld, indicating that humans and possibly other species in Skylands originated there. It also implies that certain entities in Skylands know all about Earth.