In the Avatar's universe, the spirit world exists in two different "forms". The first exists in the mortal world. Both humans and spirits can enter this world, but once in this world there is no way to contact any human or creature still in the "physical" world. Others are unable to touch or feel you, hear you or speak with you. You're also colored in a blue tint, all your color is gone. You can enter this world by being in the presence of a spiritual statue, ;ike the one of Hei Bai in the Earth Kingdom forest we saw destroyed in Chapter 1.7.
The second is an actual world, filled with spirits, and some humans. It takes much more concentration and meditation to get into this realm. Most spirits make their home here, or at least travel to this area. There are lots of trees and plants and such in this world. Spirits here don't like to be bothered because they're meditating. While it's impossible for actual humans to go into the world, your spirit can go. For example, in the season 1 finale, Aang's spirit went into this world, but not his physical body.
Most spirits can exist in both worlds; however, several spirits, such as Tui and La, exist only in the mortal world. Avatar Roku and Hei Bai, however, have been spotted in both realms.
Below in our Psychēdex, we look at each of the main spirits in each of these worlds. Spirits will be added as they appear in the show.
