Veil

The Veil between Worlds
The Veil is the common name for the barrier that is understood to exist between our world and the Outside.

Almost nothing is known about the nature of the Veil, just as almost nothing is known about the nature of what lies beyond it. It is assumed that this Veil exists because it is the simplest explanation for the events observed during The Breach and Hell on Earth.

Assuming the Veil exists at all, it functioned to prevent beings from the Outside crossing over into our world. The Veil was weakened in some way by The Breach, though not completely destroyed. The greatest damage done was reversed by Edison's Sacrifice - millions of Outsiders entered our world during Hell on Earth, but that flow immediately reversed and then stopped altogether after the Sacrifice.

While the Veil did serve to prevent crossovers before The Breach, it was apparently possible to see through it. At least some individuals claimed to be able to glimpse the Outside, though their testimony is uniformly cryptic and contains no meaningful detail. The most complete testimony came from the Voodoo Queen herself, and even she was only able to give a few details with any confidence - that there were beings on the other side, who would be willing to cross over.

The Weakening of the Veil
There are several theories concerning the nature of the Veil and the effect of the Breach. The most commonly accepted view holds that Edison's Gate cracked the Veil, in the same way a small object might crack a river dam. When the Veil was torn open at the Battle of Richmond, secondary tears "spiderwebbed" out from Edison's Gate. These tears vary in severity and in density, which is why crossovers were much more common in places than in others. It is also likely there are many places where crossovers occurred that have not been discovered as of yet.

The Veil Today
Since the Sacrifice, the Veil seems to have healed, though there remain a few oddities that suggest it is no longer as strong as it once was - places in the world that seem to follow a different set of rules than the surrounding land, and some folk who claim to be able to see glimpses of the realm beyond and affect it in small ways.