The World Border is a feature of NewSpawn which reduces the explorable area region.
Normally, Minecraft worlds have a square border sized almost 30,000 km (29999984 blocks) on each axis. However, NewSpawn originally had a size of 5 km (meaning 2.5 km distance from the center of the world) and currently has a size of 10 km. More info on the history of the border can be found on the History page.
The Border serves three main purposes:
- Keeping the density of settlements and buildings higher (in order to better "fill" the world with player-built structures)
- Preserving accessible ungenerated chunks to be populated with content from new Minecraft versions and updates
- Preventing the world file size from exceeding a reasonable size.
The size of the border applies to and is the same in all dimensions: The Overworld The Nether and The End. This however implies that all Overworld portals (built in the Nether) located at an X or Z coordinate higher than ±5000/8 (=±625) cannot be safely used: standing past the Border will steadily decrease your health points and the pace of damage is proportional to your distance from the Border. WARNING: This means that if you build a portal in the Nether past X or Z ±625, you will die, losing all your items irrecoverably.