Limbo is the border between Heaven and Hell, however, it is different from Purgatory. Limbo is also known to be the "edge of Hell". Limbo is a place or state of the souls of the just who, although purified from sin, were not allowed to enter either Heaven or Hell; or to the permanent place or state of those unbaptized children and others who, dying without grievous personal sin, are excluded from the beatific vision on account of original sin alone.

Limbo is also said to be technically the first circle of hell--includes virtuous non-Christian adults in addition to unbaptized infants. We thus find here many of the great heroes, thinkers, and creative minds of ancient Greece and Rome as well as such medieval non-Christians as Saladin, Sultan of Egypt in the late twelfth century, and the great Islamic philosophers Avicenna (Ibn Sina) and Averroës (Ibn Rushd). For some Limbo was also the home of major figures from the Hebrew Bible, who, according to Christian theology, were "liberated" by Jesus following his crucifixion

When entering Limbo, the environment changes drastically appearing as a dark, greyscale landscape and with minimalist ambient sounds, creating an eerie, haunting environment. There is not one single ounce of natural color in the world of Limbo which is said to signify the eternal loneliness and depression that a soul feels upon realizing that they will never receive any form of contact from God or their loved ones in Heaven. Limbo itself has appearances that resemble earthly locations such as forests, planes, and even cities although they appear to be in ruin and decrepit.

The difference between Limbo and Purgatory is that Limbo is permanent, as the philosopher Socrates would be there as his eternal destiny. But the souls in Purgatory were save already, they were destined for heaven. They had died believing in God and not renouncing their faith, but were not altogether clean in that they had "venial sin" (as contrasted with "mortal sin") stuck to their account. If Heaven is a state of supernatural happiness and union with God, and Hell is understood as a state of torture and separation from God then, in this view, the Limbo of Infants, although technically part of hell (the outermost part, "limbo" meaning "outer edge" or "hem") is seen as a sort of intermediate state.

The time scale in limbo is stretched out to a much higher extent than in other afterlives since it is not a level of purgatory or other realms, but a separate plane. As a result of the extreme time dilation in the plane, people in limbo can experience years in a minimal amount of time. The resulting effect on the mental state can be difficult to overcome. It is said that once a being enters Limbo, it is impossible to resurrect them as even Death itself is forbidden from ever taking a soul from the depths of Limbo.