The World Border
The World Border is a semi-transparent wall that surrounds the Minecraft world. The Border is almost 30 million blocks from both 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, 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.
History of the World Border on 2b2t
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 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 in December 7th, 2013. There they left some bedrock and two signs.
The first group to reach the sight without a backdoor was the X+ Digging Group, that reached it in March 2017. At the sight, they built point Nemo, a monument. When players heard of this, they came and griefed the place, and now the border is a very dangerous and griefed place.