Earth is the homeworld of the human race. Unbeknownst to most humans, fairies, and other magical creatures live among them, helping miserable children or causing mischief.
Fairies have apparently been active on Earth for possibly millions of years. Wanda is believed to have caused the extinction of the dinosaurs, and Cosmo is responsible for sinking the city of Atlantis. Fairies are immortal and do not age. When their godchild has grown into an adult, most fairies return to Fairy World until they are assigned to another godchild.
Earth is home to a number of humans and magical creatures that hide amongst them.