NBT is the extension given to files used by Minecraft. NBT are files used to store game data. They concern the world in which the game is played or the level. It is a binary format written by Markus Persson. NBT files can be opened and saved by a tool called JNBT (The Java NBT Library). This is a library for APIs by Graham Edgecombe. JNBT is available under a BSD license.

Minecraft is a 3D game based on traversing and building a world, the basic construction unit of which is a cube.