Overworld

The Overworld is the starting area in Minecraft. It is the only dimension that has existed throughout the development of Minecraft. The Nether was the second dimension added, in Version History. The Sky Dimension is confirmed but not yet implemented.

The Overworld is the entire three dimensional space in which in-game construction can occur, encompassing the span from the level ceiling down to bedrock and extending in every direction on the horizontal plane. It is generated through a secret process which creates multiple Noise maps to create differing elevations, general chunk shapes, and complex mountain and cave systems.

All but one of the mobs in the game can appear in the Overworld. Pigs can be hit by lightning, which turns them into Zombie pigmen, but Ghasts can only spawn in the Nether. However, it is very rare for lightning to strike a pig.

Sizes
The map can be randomly generated at the start of a game, unless it has been edited by the administrator of a server. The random generation of maps includes sheer cliffs, trees, caverns and hills.

Seeds on the other hand make a map that is generated using a complex formula. The map seems random, but is in fact generated using complex algorithms that refer to the seed entered at the beginning of the game. Part of the reason an infinite world can be generated and still take up very little space is due to this fact. If one was to share a world seed, which is just a sequence of characters that the computer converts to hexadecimal, anyone who used that world seed would generate an identical world to the previous seed, aside from any changes the players make.

In Classic and Indev, maps can be generated in "small" (128x128x64), "normal" (256x256x64), and "huge" (512x512x64) sizes.

In Infdev, Alpha and Beta maps are not infinitely big. They are made up of chunks; as the player explores the map distant chunks are generated automatically, leading to theoretically infinite maps. In practice, technical reasons force the maximum map size to 8 times the surface area of the Earth. Whilst the horizontal planes of the maps are vast in size, the vertical plane remains at a fixed 128-block height.

Chunks
Chunks are the method used by Notch to divide maps into manageable pieces. They are 16 blocks wide, 16 blocks long, and 128 blocks deep, and encompass 32,768 blocks. By adjusting the render distance, differing numbers of chunks will be loaded into memory, with "far" rendering the maximum of 81 chunks. Only chunks which have been loaded may experience activity such as spawning, despawning, growth, liquid movement, or player interaction. Upon reaching the required distance away from a chunk, it will be unloaded from the memory, however not deleted. Thus, upon re-entering that area, whatever has been changed will remain changed.

Biomes
Another subdivision of The Overworld is into Biomes. Biomes may have varying sizes, and each has its own features. For example, a forest biome will have large quantities of trees, where as a snow biome will have snow and ice.

Natural Structures
The Overworld is able to seamlessly create new areas by using patterns found in the surrounding chunks and extend those into the newly created chunk. These patterns, while unique to each world, can be categorized easily by comparing them to a real-world equivalent, such as cliffs or oceans. While Minecraft is based on landforms found on earth, impossible formations, such as floating islands, can be found throughout the Overworld.

Navigating The Overworld
Tools used for Navigating The Overworld include the Compass and Map. Neither of these will work in The Nether, and are thus unique to The Overworld. The player may also build landmarks to help orient themselves. Since Alpha 1.2.3, the key toggles a debug console which shows the player their absolute coordinates.

Light
Lighting in Minecraft affects visibility, mob spawning, plant growth, and plant retention. Lighting can be provided by the sun, torches, lava, and other objects. Note that the sun is only visible for parts of the day

Nether
The Nether is accessible via Portal and can be used for quick travel on the above ground map. The Nether also contains Block types not seen anywhere else, as well as abundant supplies of Block types found on the normal world, like Mushrooms and Lava. The Nether is home to two Mobs very uncommon on The Overworld: Ghasts and Zombie Pigmen.

Sky dimension
The Sky Dimension is a work in progress by Notch. It is now a confirmed update but the release date is not known. In a live webcast on the Swedish gaming site feber.se Notch revealed that the Sky Dimension would "probably be a dream world" and that when "you go to bed there is a certain chance that you get dragged into the dream world instead. Then you will be able to do it on purpose later on."

Void


The Void is the term given to the empty space beyond the generated boundaries of each map. It can be seen through gaps in the lowest layer of Bedrock on maps generated prior to the Halloween Update, but also simply by looking up from ground level, as the sky and the void are one and the same. For this reason, the void is a light source, and its brightness depends on the time.

Far Lands
The Far Lands is the area that forms the "edge" of the "infinite" map. When players make it to the Far Lands, they will experience an excessive amount of lag and the map will be severely distorted. According to Notch, this distortion can be fixed, but since no one is likely to make it to the Far Lands without some form of cheating, he says that he will likely not fix it since he likes the idea of a mysterious world beyond a certain distance.

Trivia

 * You can start a new world with the same map as a previous world by using the same seed.
 * There is a bug that sometimes causes the files for deleted worlds to not be deleted from your hard drive. If a new world is created with the same name, this can cause the game to reuse the old files, and thus, parts of the old map, rather than generate an entirely new map.