Minecraft wiki entry for Void, associated text: When viewed on a map, the void is seen as the pattern used for an unexplored area. This is because there are no blocks recorded in the void's area, just the same as if the player has not explored or recorded normal areas.
When falling below the void, the second to last line of the debug screen disappears entirely, and is replaced by "Outside of world..."
This also occurs when a player reaches above the height limit.
The player can survive in the void with the Regeneration effect of level 6 or higher.
In Bedrock Edition, the Void is the same color as the sky in the Overworld.
Because there is no light in the void, it can produce cave ambience.
If a player with night vision goes into the void, blocks above render as black.
Even though the New Nintendo 3DS Edition is based on Pocket Edition Alpha v0.15.4, which had invisible barriers at Y=-40, it was completely absent from this version of the game, meaning that it is possible to fall infinitely.