The different worlds...

Survive the Overworld
There is a huge Overworld in Minecraft just waiting for you to explore. On the PC this realm generates itself infinitely imto the distance so you can never explore the hole thing (although technically if you go 30 million blocks sideways the game will let you go no further). The Overworld is where you'll find the game's major components. Sections of the Overworld spawn in what are known as 'Chunks' spawn near one another. It is in the Overworld that you'll find all the friends and foes in Minecraft as well as different biomes such as forests and frozen lakes.