World border

The World Border is a semi-transparent wall that surrounds the Minecraft world. The Border is almost 30 million blocks from all four sides and is around the center of the world (Spawn, 0, 0). It was made so that players could not venture into glitched chunks. Back in the days, if you went far enough to 12 million blocks, you would reach the Far Lands, glitched terrain that would make mountains that reached the skies, and infinitely long caves. Mobs also acted weird there. And if you went even further, you would fall through the terrain, and shading did not seem to work.

The World Border is divided into the Overworld World Border, the End World Border, and the Nether World Border.

Overworld
The history of the World Border is clouded in mystery, as it was reached first sometime in 2011 through a backdoor. This is known thanks to the findings of chunks from 2011 at the -X Axis Highway. This might have been reached through Popbob's or Acid1212's (supposed) backdoor. The modern World Border was first reached by PyroByte and iTristan through their backdoor on December 7th, 2013. There they left some bedrock and two signs.

On March 26 2017, the X+ world border was reached by xxq (NTTWestJPN), rasqi, MiningMinecraft, househousehouse1, and Auion. The final stretch of digging was streamed on twitch by xxq and later uploaded to youtube. The base Point Nemo was founded at the world border and lasted less than a week. Point Nemo was griefed by Babbaj, who also wrote his name in huge fancy letters past the world border with obsidian. After Point Nemo's grief, the X+ world border area was turned into "new spawn" by Nordic93, who made a giant lavacast wall, similar to his well known ones at spawn.

End
The End World Border was first reached by Armorsmith when he took a week to fly using packetfly, lagging the server in the journey.

Nether
The Nether World Border is thought to have never been reached.(citation needed)