Chunk

A method used by Notch to divide infinite maps in the alpha and beta releases. They are 16 blocks wide, 16 blocks long, and 128 blocks deep. When wandering the world the nearest 81 chunks are loaded, arranged in a 9 by 9 grid around the player. These chunks may have activity (mobs spawning, trees growing, water flowing, dropped items disappearing etc. etc.), while the other world chunks are inactive, stored on your hard drive. If a player goes to an area that is beyond the already generated chunks, new chunks are generated and stored to the drive. As of the December 20th update, SMP servers tend to save chunks less often. Chunks will not save again if they were saved in the last 30 seconds.

Known Bugs

 * In SMP servers, some players might experience a Chunk error, where not all chunks are loaded (this is commonly known as a "Missing Chunk"). This manifests as a large hole in the map, with complete sight of The Void. If they fall into it, they will repeatedly teleport back to the position they entered the chunk at, effectively trapping them. This can be prevented by using a teleport command (non-modded servers use "/spawn" to teleport to the spawn). Disconnecting and reconnecting will reset the chunk as well.