Worlds
In the Kingdom Hearts universe, travel between worlds is normally not possible. Worlds are protected from extraterrestrial interference by an invisible shell. When the heart of a world is opened, the shell breaks apart, appearing as a meteor shower. Fragments from the wall are able to be constructed into "Gummi Ships", which serve as the main mode of travel between the various worlds. Gummi Ships are constructed from "Gummi blocks" and can be shaped into any structure; the origin of the Gummi Ship material allows for travel to other worlds. Gummi blocks can serve different functions, from navigation to offense and defense. Another method to travel between worlds are the "corridors of darkness"—interdimensional pathways which erode the user's heart with darkness. These pathways are normally used by Heartless and Nobodies, but have been used by other characters in the series.
